Witr and Nawaafil

Q:

1. Is witr Salaah waajib or fard?

2. If I pray my fard for esha and missed my witr, then is it a sin?

Q: While performing four rakaats Sunnah I forgot and completed two rakaats with salam. My question is shall I repeat all four rakaats or just offer two rakaats.

Q: Is it permissible to perform twelve rakaats of tahajjud Salaah with one salaam?

Q: I woke up for fajr and thought there was not enough time to read the sunnahs, so I read the fard. After completing the fard, I realized there was still time left, so I read the sunnahs of Fajr after praying the fard of Fajr, within the time of Fajr. are the sunnahs valid? Or will I need to redo them after sunrise?

Q: Please can I have the virtues of performing the Sunnats of fajr at home before proceeding to the Musjid for the fardh Salaah?

Q: I have many qaza namaz remaining. I want to offer a nafil namaz on Friday for 7 weeks for sharh e sadr. Can I do this or first I have to offer qaza salats?

Q: It is mentioned in the Hadith that Voluntary Worship is a means of attaining proximity to Allah. Besides the Obligatory and Essential Prayers, the Holy Prophet (Sallallahu Alayhi Wasallam) used to make arrangements for the Voluntary (Nawafil) Prayers too.

1) I want to perform tahajjud namaz daily but when I sleep I don't wake up at the time of tahajjud. So can I just offer eight rakats Voluntary Worship for Allah before going to sleep daily?

2) Is it allowed to perform extra Voluntary Worship any time of a day and any time of night before going to sleep?

Q: How must be istikhara performed? Should the dua be read after two salams? Can the dua be read in my language, I can make mistakes in Arabic and also the text we add about the particular issue in the dua I know only in my language? Is it true that istikhara for one thing can be made up to 7 times or not more than 7 times?

Q: Can we offer zuhr's four raakat sunnat-e-muakkadah after zuhr faraz namaz?