A reminder: the time for Kiddush on Seder night

Shulchan Aruch, Siman 473, se'if 1
"And if it falls on Motzaei Shabbos, he recites Yaknehaz."
(Shulchan Aruch)

A reminder: the time for Kiddush on Seder night

The first cup: The cup of Kiddush on Seder night is not merely a cup of Kiddush; it is one of the four cups.
No tosefes Yom Tov: Since the Kiddush is part of the four cups, there is no room to start the Seder early on the basis of tosefes Shabbos or tosefes Yom Tov (adding on to the holy day from beforehand). One must wait until the stars come out, and only then begin.
The root of the halacha: The korban Pesach was eaten at night, and since the Pesach was eaten at night, matzah and marror too belong to the night, and consequently the entire Seder was fixed for the night. Kiddush, on the face of it, has nothing to do with this, yet the poskim ruled that the Kiddush too is drawn along with the Seder, and so everything begins at night.

The order of Yaknehaz (Mishnah Berurah, s.k. 3)

Y - Yayin (wine): The berachah of borei pri hagafen at the start.
K - Kiddush: The berachah of Kiddush for Yom Tov.
N - Ner (candle): The berachah of borei me'orei ha'eish.
H - Havdalah: The berachah of hamavdil bein kodesh l'kodesh.
Z - Zman (time): The berachah of shehecheyanu.

"And we do not recite a berachah on besamim on any Motzaei Shabbos that leads into Yom Tov."
(Mishnah Berurah)

The reason for the berachah on besamim on Motzaei Shabbos

The soul grieves: The Rambam's expression is that the soul grieves at the departure of Shabbos, because we have lost the neshamah yeseirah (the extra soul of Shabbos).
The Gemara's exposition: The Gemara in Beitzah expounds the word vayinafash as "vai nefesh", woe, for the extra soul that was present on Shabbos has departed.
Besamim as a restorer of the soul: Since a person feels distress at the departure of Shabbos, we revive his spirit with besamim (fragrant spices). Smell is a spiritual matter, and therefore the soul, which is itself spiritual, derives pleasure from it, and through this the blow to the soul is repaired.

Support for the idea of smell from the Bnei Yissachar

The sin of Adam did not involve the sense of smell: According to the ancient conception, a person has five senses, and in the sin of the Tree of Knowledge all of them are mentioned except the sense of smell: she sees, she hears, she touches and she eats, but there is no smell there at all. In other words, there was no sin through smell.
"And the woman saw that the tree was good for eating, and that it was a delight to the eyes, and the tree was desirable as a means to wisdom, and she took of its fruit and ate."
(Bereishis)
The berachah on fragrance is derived from a separate source: The Gemara in Berachos derives the obligation to make a berachah before eating from the contradiction between two verses: on the one hand, "The earth is Hashem's and all that fills it", and on the other hand, "and the earth He gave to mankind". The Gemara resolves it: this one refers to before the berachah, and that one to after the berachah. Before the berachah everything belongs to the Holy One, Blessed be He, and one who eats without a berachah is like one who misappropriates consecrated property; after the berachah, the Holy One, Blessed be He, has granted him permission to use it. Even so, the Gemara then asks, "From where do we know the berachah on fragrance?", and brings a different verse: "Let every soul praise Hashem." From here we see that the berachah on fragrance is not an ordinary birkas hanehenin (a berachah on physical enjoyment), but a matter of spirit and soul.

Is there a neshamah yeseirah on Yom Tov?

A dispute among the poskim: There is a dispute about this, but it sits more comfortably to say that on Yom Tov there is no neshamah yeseirah.
The proof from practice: When we go out from Yom Tov into a weekday, and even into Chol Hamoed, we do not make a berachah on besamim. On Motzaei the first day of Pesach we make Havdalah on wine alone, without besamim and without a candle. The candle is understandable, since that is a law specific to Motzaei Shabbos, but the absence of besamim teaches that on Yom Tov there is apparently no neshamah yeseirah.

The difficulty: why is there no besamim on a Motzaei Shabbos that leads into Yom Tov?

The difficulty: If there is no neshamah yeseirah on Yom Tov, then even on a Motzaei Shabbos that leads into Yom Tov the extra soul departs, so why do we not make a berachah on besamim?
The accepted explanation: The Mishnah Berurah does not explain, and the explanation that is given is that there is a difference between the two situations. One who goes out from Shabbos into a weekday experiences an extreme, drastic descent, from holy to mundane, and the soul takes a blow. But one who goes out from Shabbos into Yom Tov is still within holiness, and although the extra soul departs, this is not a drastic reversal but a passage from holy to holy, and therefore no besamim are needed.

A woman drinking from the cup of Havdalah

The custom on an ordinary Motzaei Shabbos: It is accepted that a woman does not drink from the wine of Havdalah. This is a fact that has been accepted, even though the explanation is not entirely clear.
The reason given by the Shelah: In Shnei Luchos HaBris it is explained on the basis of Kabbalah that one of the explanations of the Tree of Knowledge is that Chavah gave Adam from the vine, and therefore we do not want a woman to touch the Havdalah wine, since it recalls that sin. There is also a more complicated halachic explanation.
It is not a uniform custom: There are accounts of great rabbanim, including among Ashkenazim, who gave their wives Havdalah wine to drink without any problem, but over the generations it became accepted not to give it.
On Seder night: This cup is indeed a cup of Havdalah, but it is also a cup of Kiddush and one of the four cups. Women are obligated in the four cups, since they too were part of that miracle, and their obligation is equal to a man's. Therefore she must drink from the wine, and this obligation overrides the custom that a woman does not drink Havdalah wine.
The scope of a woman's obligation on Seder night: A woman is obligated in all the mitzvos of Seder night just as a man is, except for haseibah (reclining), which is the exception.

Looking at one's hands by the light of the candle on Seder night

The practice of Rav Shlomo Zalman Auerbach: It is brought in his name, and in the name of other poskim as well, that on this Motzaei Shabbos one does not perform the usual gesture of bringing the hands close and looking at the fingernails in the light of the candle; rather, one simply looks at the candles.
It is not a prohibition: Someone who does perform the gesture is not transgressing anything; it is simply that some say there is no need for it.

The two reasons for the hand gesture on Motzaei Shabbos

Because it is a birkas hanehenin: There is a dispute as to how to classify the berachah of borei me'orei ha'eish. There is room to say it is a berachah of praise, but it is more accepted to say that it is a birkas hanehenin. If so, one must actually derive benefit from the light and not make the berachah into thin air, and therefore he performs an act that demonstrates that the benefit exists.
"We do not recite a berachah on the candle until one can make use of its light."
(Mishnah)
- The Gemara defines this benefit as being able, by its light, to distinguish between one coin and another, based on the embossing, the images and the values engraved on them, and this is difficult to see, especially when there is no other lighting.
- Since not everyone has a coin in his pocket, the custom developed to look at the fingernails and at the karnis, the white part just past the nail. If he can see the karnis, that is a sign that the light is effective and the berachah is not made in vain.
- (It was mentioned by someone in the audience that fingernails were created on Motzaei Shabbos. However, by that reasoning the halachah would apply to every Motzaei Shabbos that leads into Yom Tov, and the point is not precise, since Adam was clothed in nails.)
Because his hands are now free: So it is said in the name of one of the great authorities of the generations. In earlier times fire was a person's source of life: warmth, lighting, energy and all forms of work. On Shabbos a person is stuck with the fire and can do nothing with it, and even reading by candlelight is forbidden. On Motzaei Shabbos it is permitted to use fire, and therefore he makes the gesture to show that his hands are now free, and that he can work and warm himself by its light.
- The practical difference for a Motzaei Shabbos that leads into Yom Tov: On Yom Tov the freedom is not complete. One may transfer fire from an existing flame but may not produce a new fire, so a person is limited in his use of fire, and for this reason some say that one does not perform this gesture with the hands.

On which light do we make the berachah on Seder night?

Electric light or the candles: The question arose as to what one makes borei me'orei ha'eish on: the general lighting in the house or the candles. There are opinions that there is no need to light special candles, and one can rely on the light that is already there.
An ordinary Havdalah candle: In practice we do light a Havdalah candle, but the matter is complicated, since one should not use an ordinary Havdalah candle because of the problem that will arise afterwards with extinguishing it, and therefore we use the candles that are already burning.
The matter of a distinction: So that there should be a recognizable difference between the light of this night and the light of an ordinary Motzaei Shabbos, we do not perform all the usual actions, and from that one understands that the situation is different.

Zman - the berachah of shehecheyanu

What the berachah is on: We do not recite shehecheyanu over the food, but over the very fact that a person has merited to reach the day of the festival healthy and whole.
The proof from Yom Kippur: On Yom Kippur too we say shehecheyanu, and there it cannot be attached to a Kiddush, and nevertheless we make the berachah over the arrival of the important day itself.
Why everything was attached to Kiddush: There is no requirement that all these berachos be attached to Kiddush; it is simply more convenient that way. We combine everything into the Kiddush so that a person will not get confused and will not forget.

The woman's shehecheyanu at candle lighting

Lighting from an existing flame: We leave a flame burning from before Shabbos so that the woman can light the Yom Tov candles from it. She says "hamavdil bein kodesh l'kodesh" and then lights.
The berachos she recites: She recites l'hadlik ner shel Yom Tov and also shehecheyanu, since for her the festival is now beginning. It is accepted that she says shehecheyanu at candle lighting, and there is also the option that she not say it and instead fulfill her obligation with the shehecheyanu of the Kiddush.
The question of answering amen: A discussion arose as to whether she should answer amen to the shehecheyanu of the one making Kiddush. Since she has already fulfilled her obligation and is not obligated in this berachah, perhaps answering amen constitutes an interruption between the berachah and the drinking of the wine. Rav Moshe Feinstein and others say that she may answer amen, and we do not rule stringently on this.
A woman who says Kiddush herself: There are women who have the practice of saying the Kiddush word for word along with the husband, even on an ordinary Shabbos, because their obligation in Kiddush is equal to his and they want to say it themselves. Such a woman, who has already recited shehecheyanu at candle lighting, says the entire text of Kiddush and Havdalah, but does not say shehecheyanu, because for her it would be a berachah in vain. If she is only listening, there is no problem.
On an ordinary Yom Tov there is no difficulty: Some women light the candles before Yom Tov begins, and some say she should wait until her husband returns from shul. Either way she may say shehecheyanu at the time of lighting, since she is reciting "ner shel Yom Tov" and has thereby accepted Yom Tov upon herself; and she may also wait and fulfill her obligation with the shehecheyanu of the Kiddush. The problem arises only when the two things come together: that she recited shehecheyanu at lighting and then says the Kiddush herself.

In passing · Setting the electricity on Seder night

Setting it in advance: Remember that the electricity needs to be set in advance on a Shabbos clock, and that is the proper thing to do.
If one forgot: According to Shemiras Shabbos Kehilchasah and others, it is possible to extend the operation of the timer.

In passing · Shehecheyanu on Yom Kippur

The announcement in shul: An announcement is made that women who already recited shehecheyanu at candle lighting at home should not recite it again, and a woman who did not recite it at home says shehecheyanu in shul.
The shaliach tzibbur does not need a new garment: The shaliach tzibbur recites shehecheyanu over the day itself, and he does not need a new tallis or a new garment. Yom Kippur has no aspect of a new garment; that is a substitution of a different subject.
Answering amen: It is stated explicitly that it is proper for each person to finish his own berachah of shehecheyanu before the chazzan does, so that he can answer amen to the chazzan's berachah.