Method of Salaah

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?

Q: How can I stop stray thoughts from coming into my mind while performing salaah? What is the best way to concentrate in salaah?

Q: Tell me things in order to make myself become alright in prayers.

Q: I was reacting tashahud in the first sitting or last sitting (can't remember) of 4 rakat isha salah. I did not pronounce the small "kaaf" when I was reading "wa Rahmatullahi was barakatu" the kaaf of barakatu. So I went back to "wa Rahmatullahi" the recited from there till the end. Is my salah valid?

Q: Is it permissible to make dua in Sujood during the salaah? Also, does this dua have to be in Arabic or can it be in any language? I have heard that if dua is made in any other language other than Arabic in sujood during the salaah, then the Salaah is not valid. Is this correct?