Method of Salaah

Q: If a person recites a surah in the first rakaat and repeats the same surah in the second rakaat of a fardh Salaah, will it be makrooh?

Q: If a person recites half of a surah in the first rakaat and recites the second half of the same surah in the second rakaat of a nafl Salaah, will it be makrooh for one to recite in this manner?

Q: If a person recites half of a surah in the first rakaat and recites the second half of the same surah in the second rakaat of a fardh Salaah, will the Salaah be valid?

Q: Are the duas in jalsa and qaumah Sunnah or mustahab?

Q: Should an imam read the extra duas in jalsa and qaumah when performing salaah in jamaat? Or are these not to be read while performing jamaat?

Q: I have one major problem during salaah and that is that I cannot pronounce in the tahiyyaat the last letter (n) of the word " as saliheen" especially during the first tashahhud. So I keep repeating it, until I manage to pronounce it. If I will recite it as "as salihee" without the last letter "n" would that be also valid and the meaning still correct? Or should I recite like "as salih" without "een" at the end, like the tanween we do not recite at end of ayaats?

Q:

1. When reciting surahs in salaah, does one have to t​ake a breath after every verse or can they just pause slightly and go onto next verse.

2. What if they stop and take a breath on a part they should not and carry on reading. Like in Surah Fatiha, I sometimes take a breath just before 'ghair ril maghdoobi alaihim' even though there is no pause there. Is my Salah ok in both cases?

Q: Is it permissible for a muqtadi to offer dua after jumma namaaz instead of the Imam? Please advise.

Q: When I am Salah in the first sitting, I cannot point my big toe forward sometimes as it cramps up so I have to move forward and just sit with my toes on the floor. Sometimes I do it just before it happens even though it has not cramped up I do it in preparation for it. Will this be regarded as too much movement and invalidate my Salaah? I sort get half up and then readjust my toe and sit down.

Q: My question is that I've heard that it can be wrong to say assalamu 'alaika ayyuhan Nabiyuu because the prophet sallallahu alaihi wassalam has passed away and instead we should say al-salaam 'ala al-nabi as said by Ibn Masood in Sahih bukhari. Now, majority scholars say that we should not change tashahud after the death of prophet sallallahu alaihi wassalam but my question is Ibn Masood knows better than all of the current scholars because he was a sahaba so shouldn't we follow him because he knows better the prophet sallallahu alahi wassalam?

Another issue I have is that I came across a hadith where prophet sallallahu alaihi wassalam said that no supplication is accepted unless we send peace and blessings on him. I don't remember the source of this hadith so maybe you know. So can u tell me if it mandatory to send blessings on the prophet sallallahu alaihi wassalam every time we make dua and if we forget, that dua will be incomplete?