1) The Kaara: In Chabad we follow the custom to place the six items (Zeroa, Egg etc.) upon the Matzah cover without any dish(es) in between. However, a flat plate/tray should be placed beneath the Matzos.1
2) On both Seder nights, Kiddush should be made after nightfall.2
3) Drinking the Four Cups of Wine: According to some Poskim one should drink the entire cup; one who drank the majority of the cup is yotz’e bedieved. Others maintain that drinking the majority of a Revi’is of wine is sufficient, even if the cup contains much more wine. In order to fulfill both opinions, one who has difficulty in drinking a lot of wine should use a smaller cup that contains a Revi’is or slightly more.3
4) When reciting the relevant berachos, each of the Four Cups should be held three tefachim (24 cm) above the table.4
5) The males are obliged to drink each of the Four Cups while reclining. If one forgot and drank the 2nd cup without reclining: drink another cup without repeating the berachah. If you forgot to recline when drinking any of the other cups, you should not repeat.5
6) The earlier custom was that the women would listen to the Kiddush recited by the man leading the Seder, much as on every Shabbos or Yom Tov. Of late many women prefer to recite Kiddush themselves at the Seder nights. Either way is perfectly acceptable. Just remember not to say Shehecheyanu, since you have already said it when lighting the candles.
7) One suffering from diabetes (or another condition which does not allow them to drink wine or grape juice) can use tea or coffee for the Four Cups. This, however, presents us with a problem: the 2nd cup is poured before Mah Nishtanah, and by the time it is to be drunk it will be cold. [This problem applies for the 4th cup too]. Due to the circumstances this patient may rely on the presence of the ‘2nd Cup’ in front of the others at the Seder, but at the right time to drink a fresh cup of tea instead.6
8) At Urchatz we wash our hands without saying the Berachah Al Netilas Yadayim. What should I do if I did say that Berachah?
A. In a Sichah the Rebbe said that you should eat Matzah immediately, before proceeding with Karpas, Maggid, Maror, Korech.7
9) Yachatz: If at the end of Maggid one realized that one had forgotten to break the Matzah earlier, one need not repeat Maggid.8
10) Matzah: Each person, man or woman, is obliged to eat a Kezayis of Matzah. At Motzi-Matzah, those who have their own Kaara should eat approximately 1/3 of the top Matzah and 1/3 of the middle Matzah. Those who do not have their own Kaara should have approximately ½ of a Matzah.9
11) The above amount of Matzah is to be eaten within a time-frame known as K’dey Achilas Pras. This is generally assessed as somewhere between 4-7 minutes. The timeframe does not begin from the Berachah, nor from when putting the Matzah into one’s mouth, but from when one begins to swallow.10
12) As on every Shabbos and Yom Tov, everyone should partake of the Lechem Mishneh, the whole loaves upon which the Berachah HaMotzi was said.11 Those who do not have their own Kaara will take a Kezayis of Matzah from elsewhere. Nevertheless the leader of the Seder should ensure that everyone gets a small piece from his top and middle Matzos.12
In order to avoid too much of a pause between the Berachos and eating, the leader should designate someone to whom he will give a piece of each of the said Matzos, for distributing to all who do not have their own Kaara.13
13) The Matzah for tonight is designated as Lechem Oni. This term is given two interpretations: 1) ‘Bread of the Poor’: the poor tend to eat only part of their loaf now, leaving some for later. It is for this reason that the middle Matzah is broken in half before Maggid; 2) ‘Bread of Response’, in the presence of which the father has responded to the child’s questions.14
Accordingly it is recommended that the additional Matzos [to be used for the Kezeysim of those who do not have their own Kaara] should be upon or near the table where Maggid is recited.15
14) It is imperative that the first Kezayis of Matzah is eaten before midnight. One who was delayed until after midnight should certainly still eat Matzah, but should omit the berachah Al Achilas Matzah.16 [This is a much more basic requirement than the well-known endeavor — to eat the Afikoman before midnight17 ].
15) One who fell asleep during the meal may eat the Afikoman upon awaking. Even if he dozed off in middle of eating the Afikoman, if other people with whom he ate are awake, he may resume. If there are no others, or if they too fell asleep, he may not resume eating the Afikoman.18
16) The Cup of Eliyahu should be poured before opening the door for Eliyahu HaNavi. The Rebbe would sometimes pour this cup before bentching.19
17) If after drinking the 3rd cup one realized that he forgot to say Yaale v’Yavo in bentching — one need not drink a cup of wine after repeating the bentching.20
18) If after the Seder one vomited and threw up the Matzah one has still fulfilled the Mitzvah and need not eat again.21