Sajda-e-Sahw

Q: If a person forgets to make Sajda Sahw and has made both Salaams can he still make the Sajda Sahw and does he repeat Attahiyaat, Durud and dua after Durood?

Q: If a person was supposed to make Sajdah Sahw but forgot and made both Salaams, then what should he do? Can he make Sajdah Sahw immediately or should he repeat the Salaah?

Q: If in a four rakaat fardh salaah, one forgets to recite a Surah after Surah Faatihah in the second rakaat and only remembered when he sat for the first qadah, should he recite a Surah in the third rakaat after reciting Surah Faatihah?

Q: If in a 2 rakaat prayer one does forget to read a surah after surah al Fatiha in the 1st rakaat, should he read two surahs in the 2nd rakaat after surah al Fatiha? If yes, is this Waajib to do so, and what if one wilfully does not do it?

Q: An Imaam said Allahu Akbar in stead of Sameallah who liman hamedah. He did not make sajdah sawh. A brother got angry and made him repeat the salah. The Imaam was not present on this day hence the chaos. My question is this:

1. Was sajad sahw necessary?
2. Does the salah go through with out it?
3. Did they have to repeat the salah?

Q: 

1. In salaah I was reading a surah after surah fatiha. As I was reading it I wasn't sure if I read my surah fatiha, so I started from the beginning with surah fatiha. Is my salaah accepted?
2. In the future if I forget if I read surah fatiha what should I do? Should I make sujdah sahu , or as above?

Q: After reading a fatwa on islam-qa I am somewhat over concerned cautious in doing the takbirat, tasmi, tahmid inbetween the postures, and I mostly end up doing sajdah sahw as precaution. What is the solution for me?

Q: If I, after having read a short bit of sura whilst praying, forget the remainder of the sura, and change to reading another sura in order to fulfil the wajib amount of qira'a, do I have to do sajda sahw?

Q: What is the case if one recites in his Salaah:

1. Surah fatiha (right after one another) twice in one of the first two rakats.
2. Surah fatiha after the surah one has read after surah fatiha.
3. Surah fatiha twice in the last two rakaats.
4. At-tahiyyaat twice in the first sitting.
5. At-tahiyyaat twice in the last sitting one after another.
6. At-tahiyyaat again after the durood ibrahimiyyah
7. Durood ibrahimiyyah one after another.

In which cases one must repeat the prayer as makruh tahrimi act was carried out?

Q: If the follower (muqtadi) intentionally omits a necessary action (wajib) or intentionally commits an action that is prohibitively disliked (makruh tahriman) while praying behind the imam, is it necessary (wajib) for him or her to repeat the prayer? Things like leaving out at-Tahiyyaat, or reciting behind imam, reciting at-Tahiyyaat twice etc.