Method of Salaah

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).

Q: Can we say aameen in sajdah after making dua? Also, when we make dua after the durood in salaah, can we say aameen?

Q: I have heard that in Surah Fatiha اَلۡحَمۡدُ has to be pronounced from the throat otherwise the meaning will be changed. I pronounced all my previous prayers without pronouncing it from my throat, are all my previous prayers invalid and do I have to repeat them?

Q: Whenever I do the two sajdahs and sitting in between, I do it quickly. However, I make sure to properly sit on my legs before doing the second sajdah. as long as I do this, is it ok if this process is done speedily?

Q: My question is regarding the order of recition of Surah's in namaz. We are students and I was the imaam for fajr. In first rakat, after Surah Faatihah, I recited Surah Nasr and in the second rakat, after Surah Faatihah I recited the first 3 verses of Surah Mulk. Was the namaz totally wrong and needed to be offered again?

Q: What is the sunnah qiraat for the different salaah, and is it sunnah to recite it in all the salaah (i.e. sunnah, witr and fardh) or only the fardh salaah?