If you are busy with something important such as taking care of your daughter or an elderly mother or orphan children, there is nothing wrong with praying Tarawih at home if you are unable to go to the mosque.

If the Muslim prays Witr then he wants to pray Qiyam Al-layl after that, he should pray them two by two, and he does not have to repeat Witr.

There is nothing wrong with delaying `Isha’ prayer in Ramadan on condition that the Imam does not delay the prayer so much that he causes hardship to the members of the congregation.

The one who prays eleven rak’ahs is doing well and is following the Sunnah. Whoever makes the recitation shorter and increases the number of rak’ahs is also doing well. For more, please see the detailed answer.