1) On all eight days of Chanukah, complete Hallel is said. (Shulchan Aruch 683:1) If one accidentally only recited a “Chatzi Hallel” (he omitted the chapters of Lo Lanu and Ahavti), he should repeat the complete Hallel without reciting the Brachos at the beginning and end of Hallel. (Ishei Yisroel page 481, regarding Hallel on Pesach, citing the view of Harav Wosner zt”l in Shevet Halevi 7:62. See, however, Rivevos Efraim 4:105 who maintains that one should recite the blessings as well.)
2)The Zohar Hakadosh (Shemos 12a) writes that during the months of Teves, Av, and Tamuz the middah of din, judgement, is very pronounced in the world. The Minchas Elazar of Munkatch (3:66) writes that based on this teaching of the Zohar, the Rav of Rozvadov zt”l encouraged his children not to marry during these three months. Similarly, the Lubavitcher Rebbe zt”l (Igros Kodesh Vol. 18 Page 16), in a letter to one of his followers, writes that, “Our custom is not to make weddings during the month of Teves.” Perhaps the reason that Chabad Chassidim refrain from marrying during the month of Teves is due to the words of the Zohar Hakadosh. Sqaure Chassidim also refrain from making weddings during the month of Teves. (Netai Gavriel Nisuin 48:37) However, the Minchas Elazar continues to note that the common custom is to allow for weddings to take place during the month of Teves. Harav Gavriel Zinner shlit”a, citing the Pupa Rebbe zt”l, explains that everyone agrees that one is allowed to get married during Chanukah, even though a few days of Chanukah take place during the month of Teves. (Netai Gavriel ibid.)
3) It is a mitzvah for a mourner to serve as the chazzan during the eleven months that he recites kaddish. (Rama 376:4) The poskim debate whether a mourner may serve as the chazzan onChanukah: A- Some say that he may serve as the chazzan for Mincha and Maariv, but not for Shachris since Hallel is recited. (M.B. 684:1) B- Some disagree and hold that he may serve as the chazzan during Shachris until after Shemoneh Esrei, but should be replaced for Hallel. (M.B. 581:7, citing Machatzis Hashekel) C- While some poskim hold that a mourner does not serve as chazzan at all during Chanukah. (M.B. ibid, citing Gra) Many chassidim follow this last view. For normativa halacha, one should follow his family custom.
4) The Shulchan Aruch (670 1,3) rules that one may not deliver a hesped, eulogy, on Chanukah. However, a eulogy for a talmid chochom in his presence is permitted. Harav Neventzhal shlit”a cites Rav Yosef Chaim Zonnenfeld zt”l, who refused to discuss negative news or sad reports on Chanukah. He felt that talking about something depressing is akin to delivering a eulogy and is not appropriate for Chanukah. (BYitzchak Yikareh 670)
5) On Chanukah, when lighting the menorah, one should not speak between the brachos and the beginning of the lighting of the candles. If one did speak, if the conversation concerned the lighting itself, he is not required to repeat the brachos. If the conversation did not concern the lighting, he is required to repeat the brachos. (See M.B. 432:5 and Laws ofChanukah by Rav Shimon Eider page 28) Preferably, one should not speak until he completed lighting all the candles. However, if he spoke after lighting at least one candle the brachos are not repeated. (Laws of Chanukah ibid.)
6) The poskim debate whether one should light the Chanukah lights before reciting Havdalah this Motzei Shabbos, or is Havdalah recited before kindling the Chanukah lights. (See Shulchan Aruch, Rama, Mishnah Berurah and Biur Halacha 681 for full discussion) In shul, the custom is to light Chanukah lights first. At home, however, since there is basis for both views, one should continue to conduct himself according to his own custom. If one has no specific custom he should perform Havdalah first and then kindle the Chanukah lights. (Opinion of Harav Yosef Eliyahu Henkin zt”l cited in Luach and of Harav Shimon Eider zt”l in Halachos of Chanukah page 44)
7) During Chanukah, many refrain from visiting the cemetery on the death anniversary of relatives, because such a visit is liable to evoke tears and eulogizing, acts forbidden during Chanukah. Instead, they visit the cemetery before or after Chanukah. Others do not refrain from going to the cemetery on Chanukah, and this is the practice of some Ashkenazi communities. (See Gesher Hachaim 29:5) However, all permit visiting the graves of the righteous duringChanukah (Ben Ish Chai) (See also Yalkut Yosef Kitzur Shulchan AruchChanukah who cites those that are strict but who concludes that “those who act leniently have whom to rely on).
8) From a half hour prior to the time of lighting the menorah (approximately 10-15 minutes before sunset) one may not eat. (M.B. 672:10) A snack, however, is permitted. (Halachos of Chanukah by Rav Shimon Eider page 22) The definition of snack, for this discussion, is fruit and drinks. One may also eat bread and mezonos less than the size of a volume of an egg. (see Piskei Teshuvos page 479). The custom is for women to refrain from eating as well, even though they don’t light themselves. However, if a woman is not feeling well she may eat. (Bitzeil Hachochma 4:58 and Netai Gavriel Chanukah 5:5) If one wishes to eat before lighting the menorah (for example he will be at work late and won’t light for hours) he should appoint a shomer to remind him to light and this will permit him to eat. (Netai Gavriel 5:6)
9) The time for lighting the Chanukah candles on Friday is after Plag Hamincha, before sunset, and should burn a half hour after Tzeis Hakochavim. Therefore, care should be taken to see that there should be enough oil in the Menorah at the time of the lighting, to burn for the required amount of time.
10) One should preferably daven Mincha first and then kindle the Chanukah lights. However, if this is not possible, one may light first and then daven Mincha. One should rather daven Mincha with a minyan after lighting the Chanukah candles, then daven alone before lighting the candles. (See Shulchan Aruch 679 and Mishnah Berurah 2)
11) On Erev Shabbos, the Chanukah lights are kindled before the Shabbos candles even if a man is lighting the Shabbos candles. The reason is that there is a view which holds that men are mekabel Shabbos when he lights the Shabbos candles and melacha is prohibited. Although most poskim disagree with this view, and feel that men are not mekabel Shabbos when lighting the Shabbos candles, the custom is to preferably conduct himself accordingly.
12) However, if a man lit the Shabbos candles and did not intend to usher in Shabbos, he may kindle the Chanukah lights afterwards. This Halacha concerns a man, who does not accept Shabbos by lighting the Shabbos candles. However, when a woman lights the Shabbos candles, the custom is that the she does accept Shabbos and is prohibited from doing any melacha. Therefore, if she should, accidentally, light the Shabbos candles, she is no longer permitted to kindle the Chanukah lights. She should, instead, instruct another person to light for her (as long as it is before sunset) and recite the blessing “Lehadlik Ner Shel Chanuka” on her behalf. She may, however, recite “Sheasa Nissim”. (Mishnah Berurah 679:1)