Can I start fasting based on the moon sighting of another country?
You must follow the moon sighting of the country you are in.
Is it a condition for I‘tikaf to be performed in the mosque?
Yes, for I‘tikaf to be valid, it must be performed in a mosque. I‘tikaf is not valid if performed at home or elsewhere.
A group of about thirty young men will go to a farm on Friday. Is it permissible for one of us to deliver the sermon (*khuṭbah*) and lead us in the Friday prayer, or is it necessary to go to the nearest mosque?
All praise is due to Allah, and peace and blessings be upon our master, the Messenger of Allah.
The Friday prayer (Jumuʿah) is not obligatory upon a traveler, whether his journey is long or short, if he leaves his place of residence before the time of Fajr begins, according to the Shāfiʿī school. If, however, he sets out on his journey after the Fajr adhān, then he is obliged to perform the Friday prayer, whether in his own town or in any town where the Friday prayer is held.
It is stated in Bushrā al-Karīm (Vol.1/p.383), one of the books of the Shāfiʿī school: “[The Friday prayer] is not obligatory upon a traveler on a permissible journey, whether long or short, if he departs from his place of residence before dawn.” End quote.
Accordingly, if you set out on your journey after Fajr, you are obliged to perform the Friday prayer in the mosque. The same applies if you set out after that, since you would not have fulfilled the conditions for the validity of the Friday prayer, among them: that it be attended by forty men who are free, adult (bāligh), sane, and settled residents of the place where Friday is held. It must be held within a cluster of connected buildings, whether a city, a village, or a district (liwāʾ), for what counts is the gathering of the buildings. And Allah Almighty knows best.
Is it recommended (mustaḥabb) for the one offering a voluntary sacrifice (uḍḥiyyat taṭawwuʿ) to eat from its meat?
In the Name of Allah, and may peace and blessings be upon our Master, the Messenger of Allah.
It is highly recommended (Mustahabb) for the person offering a voluntary Udhiyah (sacrificial animal) to eat from its meat, but it is not an obligatory requirement (Wajib). Allah the Almighty says {what means}: "So eat of them and feed the needy who do not beg and the beggar. Thus have We subjected them to you that you may be grateful." (Al-Hajj/ 36)
"So eat of them": This directive is an encouraging recommendation, not a binding command.
The Qani’ (the needy who do not beg): Refers to a poor person who refrains from asking people for help out of dignity.
The Mu’tarr (the beggar): Refers to a poor person who explicitly asks others for assistance. And Allah the Almighty Knows Best.