Method of Salaah

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?

Q:

1. If I came up from first sajdah without keeping my hand on my thigh and then go for the 2nd sajdah, does this affect my prayer?

2. If my knee raised a little after my first sajda, does this affect my prayer?

Q: If I recite few words of Surah Fatiha or attahiyyat after rising from first sajdah and then go back to 2nd sajdah, is my prayer valid or do I have to do sajdah-e-sahw?

Q:

1. What is the status of tasbeeh of rukoo and sajdah? Fardh, waajib or sunnah?

2. What if in an individual salaah one does not recite the tasbeeh of rukoo or sajdah, is the salaah valid?

Q: If the imam makes a recitation as short as the first three ayahs of Surah Al-fajr, or the first three ayahs of Surah Yaseen, will the prayer be valid?

Q: I recited the last few aayahs of Surah ar-Rahmaan in the last rakaat of witr, but I skipped the second-last and third-last aayahs by mistake. Is my salah valid?