Witr and Nawaafil

Q: Can one pray nafl salah after having prayed sunnah salah if time permits before the jamaat for the fardh salah starts?

Q: Can a waladuz zina (illegitimate child) make imamat for taraweeh salaah in Ramadhaan?

Q: Could you please inform me about the minimum rakaats of Tahajjud namaz and can I perform it about 20 minutes before fajr azaan? 

Q: Can I perform one rakaat witr or is it compulsory to read three rakaats witr?

Q: Can we perfrom Tahajjud Salaah without sleeping because I am awake the whole night till fajar? 

Q:

1. Is it compulsory to pray sunnat-e-muakkadah namaaz immediately after finishing the farz namaz?

2. Can I pray farz namaz with jamat in the masjid and then go home and pray the sunnat-e-muakkadah namaz?

Q: I have a lot of gas when I wake up in the morning for fajr. It is almost an everyday thing. Sometimes the feeling for breaking wind is strong and I pray the fardh prayer first then the sunnah 2 rakahs in case I miss the prayer if I have to break my wudu. Is that valid given my situation of having lots of gas in stomach?

Q: Does one have to make qadhaa of sunnah salaah?

For example, if a person misses the sunnah salaah for Zuhr, and performs 'Asr, should he perform the qadhaa of Zuhr sunnats?

Q: I made istikhara (2 prayers after ishaa and dua) but I got no response. I made it many times before but got no response.

My question is, can I make istikhara dua before I go to sleep? Can I pray 2 rakats istikhara after ishaa and then make the istikhara dua just before I go to sleep? 

Q: Is it permissible to perform two rakaats nafl salaah as sukr to Allah for all His bounties?