Qiraat in Salaah

Q: Is there any qawl amongst the ulama which stats that the sunnat qiraat in salaah is not which surahs are recited but rather the amount recited?

Q: Besides reading a complete Surah or atleast three ayaats of the Quaran after Suratul-Fatiha in salaat, I understand one long ayaat can instead too be read. But how long should the ayaat be and on what basis is the length calculated?

Which long ayaats (if any) are generally deemed preferable to read?

Q: With regards to Friday Fajr salaah: If I read Surah Sajdah in 2 rakaats one week, and the next week read Surah Dahr in 2 rakaats, will I get the fadheelat of the sunnah? Because the musallees are old, and they do not like to read long salaah. For this reason, can I get the reward for the sunnah?

If there's no sunnah reward for this, then how can I get the sunnah reward?

Q: Can I repeat the same Surah in each rakaat of salaah?

Q: Is salaah valid if someone does not pause after every aayat of a surah?

Q: If one was reading the qira'ah in salaah with an audible voice, then read without moving the lips a few times, will the salaah be invalid?

Q: In salaah, after reciting Surah Faatiha, if a person is reading from the middle of a surah, is it preferable to read bismillah or not to read bismillah.

Q: If due to sensitivity, the microphone picks up the Imam's voice in the 3rd and 4th rakaat of Zuhr, Asr, Esha and in the 3rd rakaat of Maghrib, does that count as having made Qiraat in a loud voice? Is Sajdah Sahw wajib? Please note that the Imam is not intentionally doing so... He is keeping the voice low but the mic picks it up.

Q: How loud can a person recite Quraan in salaah like in a fardh or sunnah salaah? How loud should a person recite when he is performing salaah individually in his room, etc. in a jehri or sirrri salaah? 

Q: What is the shar'ee ruling in the case where the Imaam recited the same surah in both rakaats of a fardh salaah? Will sajdah sahw be waajib?