Method of Salaah

Q: While praying fajr salaah, I got up from ruku, but I was not totally straight. Is my salah valid?

Q:

1. Is reciting bismillahir rahmanir raheem before alhamdu in namaz obligatory? If one doesn't read bismillah before alhamdu, either in the first or second, third or 4th rakaat is their salah nullified?

2. Is reciting rabbigh firli in between sajadah obligitory? If one doesn't recite this inbetween sajda and just says subhana rabbiyal a'ala in sajadah and sits and says Allahu akbar and then goes into sajadah again and says subhana rabbiyal a'ala, is this incomplete and is the namaz nullified because the believer didn't say rabbigh firli between the sajadah?

3. Is it obligitory to say bismillah before or after any surah during namaz? If one doesn't, is their namaz invalid?

4. If a woman reads silently where her lips and tongue is moving but you cannot hear her, are her prayers invalid? She lives in a joint family, where her husband's cousins, both male and female come and go and she cannot say for sure who is at home and who isn't. It is a 3 floor house, with she occupying one room and the opposite room belongs to her husband's uncle and her husband's cousins.

5. If a woman has been praying normally but hasn't been saying bismillahir rahmanir raheem before surah fatiha (as in scenario 1) and hasnt been saying rabbigh firli in between the sajadah (scenario 2) and hasnt been saying bismillahir rahmanir raheem before or after any surah in namaz (as in scenario 3), and has been reading quietly and has been moving her lips and tongue and no one is able to hear her, has all her namaz been invalid if she has been praying like this? She was unaware that a woman is to pray aloud she knew reading quran should be read in a tone one can hear themself but she didnt know you are suppose to hear yourself during namaz 

Q: Can I recite first kalima in sujood as Dua, La ila ilaha illallah muhammadur rasulullah.

Q: If the Imam recites "الرحمان الرحيم" with ه or in such a manner that you can’t tell if it’s a "ه" or "ح" then is Salaah broken? The Imam is capable of reciting “ح" with tajweed but recites too softly like this almost all the time.

Q: During Fajr prayer I made a mistake in Surah Dahr. Instead of و يَطُوفُ عليهم ولدان مخلدون I recited و يُطافُ عليهم ولدان مخلدون. Is my prayer valid?

Q: During Friday prayer, the imam made the following mistake during recitation: In سورة البقرة ، آية ١٣٦ ، instead of لا نفرِّق بين احد منهم , he recited لا نفرِّق بين احد من رَّبِّهم Is the prayer valid?

Q: Can we read two (2) separate Surahs in one rakat of a farz namaaz? For example, I read Surah Kafiroon and Surah Ikhlaas in the first rakaat of Fajr farz namaaz. 

Q: Sometimes when I'm offering my salaah, my kids start to argue with each other or start reciting some surah. As a result my attention gets diverted. In this situation I read Allahu akbar (when going into ruku or sajadah) in a bit loud voice to stop them from disturbance. Is this a sin?

Q: While offering qaza of esha salaah, I made the following mistake during the recitation of aayat 15 and 16 of Surah Fajr, instead of فَيَقُولُ I recited فَيَقُولَ. Is my prayer valid?

Q: Could you please specify how to read all the rakaats of Zuhr Salaah:

E.g. Zuhr - Four Sunnah (Surah Faatihah and a Surah in all four rakaats) then four fardh (Surah Faatihah and a Surah in the first two and in the second two, only Surah Faatihah), then is two Sunnah (Surah Faatihah and a Surah in both rakaats) and last for Zuhr is two nafl (Surah Faatihah and a Surah in both rakaats).