Salaah

Q: In the musjid if someone is praying and someone goes past him with out knowing does it break his salah?

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: Is it waajib or mustahab for a mustahaza to clean herself for each Salaah?

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: A person arrives late to the masjid and misses a number of rakats with the imam. When the imam says salam, he thus has a number of extra rakaat to make up. But he doesn't remember how many. In order to find out, may he pray slowly and see how many extra rakaats the people around him do, since they joined the prayer at the same time as him?

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

Q: If I reach the musjid at a time when the jamaat of Fajr has already commenced, should I immediately join the jamaat or should I first offer the sunnah of Fajr?

Q: It is permissible to offer Qadha salaah after 'Fajar' and 'Asar' prayer?

Q: We are university students in Canada who have final exams coming up. Some of which are from 2pm to 5pm. However, Asr Mithl to Maghrib is from 2:10 to 4:30. How should we pray our Asr Salah assuming we cannot pray during the exam?

Q: In the UK the weather is often cold and wet and I am a young teenager. Sometimes I want to go to pray salah with the jamaat but due to the weather my mother stops me fearing that I will become ill. Shall I disobey her and fulfil Allah Ta'ala's command or obey her and read at home? Would I get a sin for not obeying my mother or missing salah with jamat?