Jamaat Salaah and Imaamat

Q: I caught Maghrib Salaah in the 1st tashahud and on completing salaah I realized that I have completed 4 tashahud in a 3 rakaah salaah. Was this correct? If not, do I need to make Qazaa?

Q: I have been offered by my uncle to perform taraweeh salaah with two cousins of mine at his house. His house is between a musjid and a jamaat khana and is 650m from both. I wanted to find out if we are performing taraweeh there, can we perform the esha salaah there as well or not? 

Q: I would like to know that when should we begin salaah with the imaam, after takbeer in namaz or before namaz. Can a person do itteba of imaam when he makes the niyat?

Q:

1. Is it permissible to pray behind an Imam who smokes?

2. Also, is it permissible to learn Quran from someone who smokes cigarettes?

Q: If due to rain in certain parts of the world, Maghrib and Isha’ are prayed together in the masjid. Would it be permissible for Hanafis to conduct a second congregational Isha’ prayer in that masjid, because it is forbidden to conduct second congregation prayer in a masjid?

Q: Some masaajid have a two-storey building. Is the reward for praying in the first row of the second floor equal to that of praying in the first row of the first floor?

Q: Suppose we are offering 4 rakaaat namaz as a muqtadi and we are in the 2nd rakat of prayer and as we know in the 2nd rakat we are suppose to say only "At-tahiyyaat" but mistakenly you also said Durood Ebrahim, then what should one do if he is offering the namaz as a muqtadi?

Q:

1. In Witr Salaah in the month of Ramadhan, if the masbooq joins the Imam in the ruku of the last rakat, is it wajib for the masbooq to recite dua e qunoot when he stands up to complete his missed rakat and in which rakat will he recite dua e qunoot?

2. In Witr Salaah, if the masbooq missed all the rakaats and did not recite dua e qunoot when he stood up to complete his Salaah, is it compulsory upon him to repeat the Witr Salaah after the Salaah time has expired?

3a. If the masbooq turned for salaam with the Imam accidentally or not knowing the masala and he did sajdah sahw at the end, is the Salaah valid?

3b. In the above situation, if he didn't do sajdah sahw, is it compulsory to repeat the Salaah when the Salaah time has expired or is the Salaah valid but incomplete?

4a. When the Imam did salaam to do sajdah sahw, the masbooq accidentally or not knowing the masala, he also turned his head for salaam and then did sajdah sahw at the end of the Salaah, is the Salaah valid?

4b. In the above situation, if he didn't do sajdah sahw, is it compulsory to repeat the Salaah when the Salaah time has expired or is the Salaah valid but incomplete?

Q: If a husband and wife would like to peform jamaat salaah at home, would they stand just like how two people would normally stand?

Q:

1. Suppose I am offering Asar or Maghrib and I joined the Namaz in the last Rakaat after missing the first three rakats, now when the prayer ends with "Assalaamu alaikum warahmatullah" by Imam and I get up from "Attahiyyaat", Then what do I have to say first? Do I have to start my next rakat with thana or bismillah?

2. Also, do I have to say a surat after reciting surah fatiha?