Eating and doing Melacha before candle lighting:
Half hour prior to candle lighting: Some Poskim rule one is to refrain from working, eating and learning Torah a half hour before the time of candle lighting. [Hence, those who light after nightfall, abstain from the above activities starting a half hour before nightfall, while those who light after sunset, abstain from the above activities starting a half hour before sunset.] Nevertheless, those who light after sunset, may be lenient to learn Torah until the actual time of sunset arrives.
Appointing a Shomer: If one asks a friend to remind him to light candles later on, then he may eat, learn Torah or perform mundane activities prior to lighting. However, this only applies so long as his friend is not involved in the above activities.
If one is eating out by a friend/relative on one of the nights of Chanukah, may he eat prior to lighting candles?
He must either return home and light candles prior to the meal, or appoint a Shomer to remind him, in which case he can light after the meal, upon returning home.
May an employee, employer, business owner work past nightfall during Chanukah?
All employees and business owners are to arrange to be home from work by nightfall, so they can light the candles at its proper time. If they are unable to do so, then the following options are available: a) Have one’s wife light instead of him at home, at the proper time. b) If he eats all his meals at work, he can light the candles there at its proper time. c) To appoint a Shomer to remind them to light candles, as explained next, and they will light upon coming home.
Q&A on meal
May one eat a snack prior to lighting candles?
Definition of snack: The definition of a snack is up to 57.6 grams of bread [or Mezonos] and 57.6 grams worth of an [alcoholic] beverage. One may drink an unlimited amount of other liquids, such as water, tea, and coffee, and eat an unlimited amount of fruits.
Q&A on other people
May women who are being Yotzei with their husband/father eat a meal and perform work prior to the lighting?
The custom is for women not to perform work, just as is the law regarding a man who is lighting. However, in a time of need, she may be lenient.
May one who was appointed as an emissary to light on behalf of someone else eat and do Melacha prior to doing so?
Yes, so long as they have already fulfilled their obligation.
 M”A 672:5; Rashal 85; Bach 672; Kneses Hagedola 672; Olas Shabbos 672; Peri Chadash 672:1; Elya Raba 672:1; Beir Heiytiv 672:2; Chayeh Adam 154:20; Ben Ish Chaiy Vayeishev 7; Mishneh Berurah 672:10; Kaf Hachaim 672:4
 See Shaar HaTziyon 672:14; Those who light after Tzeis, are to separate from Melacha from when Tzeis arrives. Those who light after sunset, are to separate from Melacha from when sunset arrives.
 The reason: One cannot say that today one may be completely lenient regarding Melacha and meals, even though the Rama holds there is no real need to light on time, being that we light inside. The reason for this is because according to all, the beginning time of lighting is either by Tzeis or sunset and goes throughout the night, and if one does not do so prior to eating or prior to performing Melacha, he may forget to do so all together. This is similar to the decree against eating or performing Melacha prior to Mincha or Maariv, or Bedikas Chameitz.
 Machatzis Hashekel 672:5; Derech Hachaim 1; Shaar HaTziyon 672:14; Kaf Hachaim 672:4
 Shaar Hatziyon ibid
The reason: As there is a dispute as to when the actual time of obligation begins, and one may thus be lenient at least in this regard.
 M”A 672:5; Rashal 85; Bach 672; Mishneh Berurah 672:10; Kaf Hachaim 672:4 and other Poskim mentioned above
 The reason: Although by all Rabbinical Mitzvas one is not required to stop if he began doing the Melacha at a permitted time [See Admur 489:17], nevertheless, since the time of Chanukah candles is within a half hour from sunset:nightfall, therefore, one needs to stop when the time arrives. [Bach; Shaar Hatziyon 672:15] Vetzaruch Iyun regarding those who are accustomed to light inside the house, in which case the time for lighting extends throughout the night. [See Piskeiy Teshuvos 672:7
 Admur 275:4 regarding reading near a candle on Shabbos; 431:11 regarding Bedikas Chametz [permits learning]; 489:17 regarding Sefiras Haomer; Rama 232:2 regarding Shema; Taz 275:3; Tzemach Tzedek 47; Birkeiy Yosef 275:3; M”B 275:6; Nitei Gavriel 4:4
Ruling of Admur in 431 and other opinions: In 431:1 and Kuntrus Achron 431:2 Admur rules that a Shomer is only valid to allow one to learn Torah, being that it is a Mitzvah, and is invalid to allow one to eat or perform other mundane activity. This follows the opinion of the M”A 275:5 that a Shomer is invalid to allow one to perform mundane activity near candles on Shabbos. [see also Nachalas Tzevi Y.D. 262:1] However, the Taz ibid rules it is valid, and so rules Admur ibid. This thus creates a contradiction in the ruling of Admur between Shabbos and Pesach regarding whether mundane activity is allowed. Perhaps however one can suggest that regarding Pesach we are more stringent. Vetzaruch Iyun. [See Beis Shlomo 48; Otzer Halachos 24; Mishneh Shleima 30:3; Pamei Yaakov 4:14; Nitei Gavriel ibid]
 See Halacha 9B for the details of why he must return home and cannot light by his host.
 Piskeiy Teshuvos 672:7
 M”B 431:6 regarding Bedikas Chametz; See also regarding Megillah: M”A 692:7; Elya Raba 692:11; M”B 692:14; Kaf Hachaim 692:36; Piskeiy Teshuvos 672:7
 Peri Megadim 431 Ashel Avraham 4; Piskeiy Teshuvos 692:8 based on P”M 431 A”A 4
 Piskeiy Teshuvos 692:8 based on M”A 232; M”B 232:35
 M”B 692:14 in name of Derech Hachaim 3; Kaf Hachaim 692:36
 M”B 431:6 regarding Bedikas Chametz; Regarding Megillah: Piskeiy Teshuvos 692:8 based on M”A 232; M”B 232:35
 Bezel Hachochma 4:58; Piskeiy Teshuvos 672:7
 See Hagahos Nachalas Tzevi Y.D. 262:1 regarding the father of the child who has appointed a Mohel
 Bezel Hachochma 4:60; Piskeiy Teshuvos 672:7