What is the ruling on performing Tarawih in sets of four rak‘ahs with only one Tasleem?
It is not permissible to combine more than two rak‘ahs with a single Tasleem in Tarawih prayer. Whoever does so, their prayer is invalid. Shaykh al-Islam Imam Muhammad al-Ramli (may Allah have mercy on him) stated: "If a person prays four rak‘ahs of the Tarawih prayer with a single Tasleem, it is not valid if they did so intentionally and with knowledge [of the prohibition]. Otherwise, it becomes an 'absolute voluntary prayer' (nafl mutlaq); because it is contrary to what has been prescribed." [Nihayat al-Muhtaj, Vol.2/P.127].
Is it valid to perform the obligatory prayer while sitting?
Praise be to Allah, and peace and blessings be upon our Master, the Messenger of Allah.
Standing (Al-Qiyam) while having the ability to do so is one of the pillars (Arkan) of the prayer; the obligatory (Faridah) prayer is not valid without it. However, whoever is unable to stand may pray sitting down. As for voluntary (Nafilah) prayers, it is permissible to pray them sitting even if one is able to stand, but the one sitting receives half the reward of the one who prays standing. And Allah the Exalted knows best.
Is it permissible to fast the six days of Shawwal before making up for the missed fasts of Ramadan?
● If a person missed fasts due to a valid excuse, they may fast the six days of Shawwal before making up for Ramadan fasts, because qada (makeup fasts) in this case can be delayed, while the six days of Shawwal must be observed within Shawwal.
● However, if a person missed fasts without a valid excuse, they must make up for the missed fasts immediately after Eid, before fasting the six days of Shawwal. If they fast the six days first, it is valid, but they must still make up for the missed Ramadan fasts afterward.
It is also permissible to combine the intention of qada (makeup fasts) and the six days of Shawwal in one fast. However, it is better to fast them separately, as this increases the reward and avoids scholarly disagreement regarding combining intentions.
Should one who doesn`t perform prayer out of laziness make it up later, and how should he/she do so?
All perfect praise be to Allah,The Lord of The Worlds He/she is obliged to make up missed prayers by offering with each obligatory prayer another one, and if he/she offers two, then it is better. And Allah Knows Best.