Method of Salaah

Q: If a person is incapable of making du’ā in Arabic during his salāh, may he make du’ā in any other language? I read that if he is able to make du’ā in Arabic, then there exists a difference of opinion in the permissibility of doing so in a different language while in salāh. According to Imām Abū Yūsuf and Imām Muhammad, it is impermissible and the prayer will not be valid.  On the other hand, according to Imām Abū Hanīfah, the prayer will be valid, but it is makrūh (disliked) to do so. Is this true? But the question is what if a person is incapable of making du’ā in Arabic during his salāh? Is it permissible without being makruh?

Q: What are the "Dua's" that Nabi (Sallallahu Alayhi Wasallam) read in last tashud after darood shareef? Is there any proof that Nabi (Sallallahu Alayhi Wasallam) used to pray "Rab be jaalnee mo qee ma asala tee............. " dua after darood shareef in Namaz?

Q:

1. Is it imperative to read diff rent surats each day in the five salaats? Would salaat be valid if one continuously recites the same surats only.  For example, in the Maghrib salaat each day, one habitually recites sura Falaq in the first rakaat and sura Naas in the second rakaat. 
2. Can Ayatul Kursi be recited in place of a sura in salaat or is it necessary to add at least two ayaats before or after ayaatul Kursi?

Q: If a person makes a sajdah on a warm hat which overlaps onto his forehead, will this be correct?

Q: Reading salaat behind Imam in jamaat, in the last two rakaat what should one recite, according to Shafii Maslak?

Q: Which is the correct method of making salaam at the end of salaah. Is it one salaam to the right and therafter one salaam to the left or does the face have to be brought back to the center after the salaam to the right and then salaam to the left.

Q: I have a question regarding Salaah. For eg. In Esha Salaah there are four rakaat's, in which two are audible and two are silent. What should we do in the last two rakaats? 

Q: A person breaks wind after having made one salaam in Salaah. Is the Salaah complete or is the second salaam waajib and he has go back and make wudhu and perfom the Salaah again?