What is the ruling on congregational prayer performed outside the mosque, and is it a condition that it be performed in a mosque in order to attain the full reward?
All praise is due to Allah, and peace and blessings be upon our master, the Messenger of Allah ﷺ.
It is not a condition for attaining the reward of congregational prayer that it be performed in a mosque; however, a Muslim should still be keen to perform his prayers in the mosque, so as not to miss out on immense reward. This is due to the virtue of the mosque and of spending time there (i‘tikāf), the typically larger number of worshippers present, and the additional reward gained through walking to and from the mosque. On the authority of Abū Hurayrah (raḍiyallāhu ‘anh), the Messenger of Allah ﷺ said: "Whoever purifies himself in his house, then walks to one of the houses of Allah to fulfill one of the obligations Allah has prescribed, one of his steps will erase a sin, and the other will raise him a degree [in status]." (Related by Muslim)
Whoever misses congregational prayer at the mosque should still strive to pray in congregation at his workplace, or together with the members of his household. And Allah, the Exalted, knows best.
How do I deal with whispers (waswasa) in ablution and purification?
Whispers in ablution are from Satan, and the Muslim should not pay attention to them. He is not required to re-perform ablution or repeat washing a limb because of waswasa. He should always base his purification on its being valid. It is recommended for him to frequently say "La ilaha illa Allah" (There is no god but Allah), because Satan recoils when Allah is mentioned. And Allah the Almighty knows best.
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 valid to perform Tarawih prayer at home?
It is Sunnah for a Muslim to perform Tarawih prayer in congregation at the mosque.
However, if a person sometimes prays it at home in congregation with their family for a valid reason, there is no harm in doing so.