Salaah

Q: What is Salaat-ut-Tasbeeh and when and how to perform it?

Q: I understand that if one laughs aloud in Salaah, his wudhu breaks, and if he laughs silently, only his Salaah breaks. However, I wish to know what constitutes a loud laugh and what constitutes laughing silently. Also, is a smile considered laughter?

Q: If "Rabbanaa lakal hamd" the word hamd at the end is sounded as a ت and not د will the salaah brake? The letters ت and د are they from same makhraaj, and so there is no zallatul qari is these are replaced by eachother not on purpose?

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: I am 7 months pregnant and suffer from backaches and leg pains. Will it be permissible for me to sit and read salaah when the pain is very severe?

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: Is it ok to sleep before esha and then wake up and perform Isha before the morning? Is it right to perform Isha at 1 o'clock? 

Q: What is the difference between Qiyaamul Layl and Tahajjud? Is it necessary to sleep before offering Tahajjud or can one perform it immediately after Esha?

Q: One has an atomic wrist-watch. That is a watch that runs exactly on the second with the atomic clock setting. If sunrise on the prayer calendar is at 7.00 and one finishes Fajr salaah at 6.59 and 58 seconds i.e. 2 seconds before 7.00 o'clock. Is the Fajr salaah valid? And what if it was finished 1 second before 7.00 o'clock?

Q: When does the time for zuhr end according to the Hanafi fiqh? Does it end when the Shaf'iee asr time starts or is it after?