Method of Salaah

Q: I read in a book that to read Sami Allahu liman hamidah, to read hamidah with a soft h i.e. a ه will break salaah. Why is that? The meaning is changed? What if it happened unintentionally?

Q: Question regarding reciting inaudibly. In my case I was praying Dhuhr Fardh and quietly as to hear my own voice, in my last (4th rak'ah) - I was reciting "Ghayril Maghdoubi" at Maghdoobi, I could only clearly hear "Ma--doobi" the Gha wasn't proper so that I could hear, but I moved my tongue to recite it as normal. Obviously I didn't want to recite "Ma--doobi", so I think I inaudibly said the gha, does this matter or affect the validity of the namaz?

Q: What is the اصح (most correct) opinion regarding when to start takbeer-e-tahreema? 

1. After raising the hands
2. While raising the hands

Q:

1. Can I say Ameen feebly (not bil jahar) or is it compulsory as I live in a Hambli environment?
2. Is doing of rafa ul yadain compulsory? Can one leave it curtesy living in Hambli environment?

Q: If a person misses a wajib of salaah unintentionally or because they did not have knowledge of the particular action, must they read the salaah again? What if this salaah is Asr salaah, can they read it again in the asr time?

Q: When I perform Salaah alone, should I recite Bismillahir Rahmanir Raheem before Surah Fatiha in every rakaat of Salaah? Also, should I recite Bismillahir Rahmanir Raheem after saying Aameen and before I start another Surah?

Q: Is it permissible to have congregational duaa after fardh salaah? The masjid I go to does congregational duaa after salaah but I have heard that this is not a sunnah practice.

Q: During tashahhud one says "..as salaamu alayka wa alaa ibaadillaah'is salihin.." instead of "..as salaamu alayna wa alaa ibaadillaah'is salihin..". Does this break salaah if left uncorrected?

Q: The is a hadith which states the recitation of ayatul kursi after every fardh salah. I want to know does it mean immediatly after fardh or after sunnat?

Q: If in "Ihdeenas-Siratal-Mustaqeem", I recited dee with a daad mistakenly instead of daal does this invalidate the namaz? I don't know for sure if I done it, but it seems likely so should I repeat the namaz or is it an acceptable mistake? I didn't repeat it afterwards.