Method of Salaah

Q: I was always of the impression that the muqtadee should recite tahmeed in qaumah after the imaam completes reciting tasmee. However, I was lately informed by certain Ulama that the muqtadee should recite tahmeed at the same time that the imaam recites tasmee. I would like to know whether this is correct? I also wish to know whether all my past salaah are valid since I have always been reciting tahmeed in qaumah after the imaam completed reciting tasmee.

Q: If a person prays 4 rakaats nafl with one salam, do you have to recite thana in the 3rd rakaat?

Q: While leading the jamaat, if a person misses one word from an aayat and does not correct it even after luqmah from a muqtadi, will sajdah sahw be sufficient to make the salaah valid?

Q: An Aalim said in the last two rakaats of a Fardh qadhaa salaah, it is not necessary to recite any surah. One may merely recite SubhanAllah/Alhamdulillah/Allahu Akbar (either one) 3 times. Is this true?

Q: When I recite my salaah, its very difficult for me to recite the word Rahman due to the sound of letter haa. The sound that comes out of my mouth is more like Raman. The rest of the recitation I don't have an issue. Is my salaah valid?

Q: I pray all my salaah but most of the time when I read salaah there is no concentration (jamaat or alone). I don't know whether my salaah is accepted or not and I also get bad doubts.

Q: While reciting qiraat in salaah, I missed the third aayah of Surah Naas (Ila hinnaas). The remainder of the surah was completed.

1) Should I have made a Sajdah e Sahw?

2) If Sajdah e Sahw was necessary, but was not made, should the salaah be repeated?

Q: Where should the gaze of a musallee be in the different positions of salaah?

Q:

1. While rising from the first sajdah, if I don't place my hands on my knees and go for the 2nd sajdah, is my prayer valid?

2. What if I forget to place one hand on my knee after the first sajdah and go for the 2nd sajdah, is my prayer valid?

3. Is placing my hands on my knees during tashahhud obligatory? If I lift my hand just to scratch my back is my prayer valid?

Q: While sitting in attahiyyat, if I lift my hand from my thigh, does this affect my prayer?