Faraaidh, Sunnats and Waajibaat of Salaah

Q: How many verses of Surah Fatiha is waajib to recite in salaah?

Q: Is it necessary to read the tasshahhud, thana, durood and dua in salaah with the rules of tajweed?

Q: Is saying transitional takbeer (Allahu Akbar) when going to ruku, sujood, qiyaam obligatory upon the individual praying behind an imam or can he just follow the imam.

I have performed many prayers behind the imam and I thought I wasn’t obligated to say the takbeer besides takbeer al ihram. Would my previous prayers be invalid otherwise even if I were unaware? 

Q: I heard from a shaik that one should move his lips while reciting azkaar in salaah or in general, and he gave the example of "one will not get sin if they think of sinning except they say or act on it. and the shaik said that so similar the good deeds!"

a. Once I read in a hadith that the Prophet (Sallallahu Alaihi Wasallam) never moved his lips in Salatul Asr. (I was not aware of the authenticity of that and I also remember that I read it from Sahih Muslim/Bukhari). 

b. I heard from another shaik that if someone around you recites anything only by moving his lips or some phrase with a sound and some without, then he said that one should warn such a person to stop it or read it clearly and loudly, if not then we have to tell them that "you are a witch person and will reveal it to everyone if you don't, (because it is an act of witches or magicians, the shaik said)" now which is correct and in which situations?

Q:

1. What is the status of tasbeeh of rukoo and sajdah? Fardh, waajib or sunnah?

2. What if in an individual salaah one does not recite the tasbeeh of rukoo or sajdah, is the salaah valid?

Q: What are the waajibat of salaah as per the Hanafi mazhab?

Q: If a wajib is left out in Fardh salah, Witr Wajib salah like dua e Qunoot or sunnat and nafl salah, is it compulsory to repeat the salah after the salah time has expired?

Q: If a person forgets to recite surah faatihah or leaves out any other waajib in a sunnat salaah and only remembers after the time has passed, does he need to repeat the salaah or not?

Q: Can one perform salaah in any language other than Arabic?

Q: When you perform salaah, when doing takbeer to start, should we look up or down? And after raising from rukuand saying "samirallahhulimanhamida", some says you have to say "allahumma rabbanawakalhamd" and others only "rabbana lakalhamd"? Which one is correct according to sunnah? And is it obligatory to say it? If i did not say it, are all my prayers invalid?