Sajdah-e-Tilaawat

Imaam going into ruku after reciting a sajdah aayat

Q: A few days ago, our imam recited Surah Alaq in the second rakah of Isha salaah. When he recited the aayah of sajdah, he did not perform the sajda-e-tilawat but went into ruku' and completed the salaah as normal. 

My question is: was he right in omitting to do sajda-e-tilawat which my understanding is to be wajib. After the salaah he explained that what he did was permissible.

Imaam going into ruku immediately after reciting the aayat of sajdah and making the intention of sajdah tilaawat in ruku

Q: In Fardh Salaah, as an Imaam, if I read an Aayah of Sajdah, can I immediately go into ruku at the end of the Sajdah Aayah? i.e. (not going down into a Sajdah Tilaawah), but making intention of sajdah in the ruku.

NB: I did this a few items without informing the congregation.

Please can Mufti Saheb inform me what is the correct thing to do.

Repeating the sajdah tilaawah aayah in a musjid or classroom

Q:

1) If I am reading a sajdah tilaawah aayah repeatedly on the same spot, then only one sajdah is compulsory. However, if I am in a musjid and I am reading the same aayah while moving around, then how many sajdahs do I have to make? Does the distance I cover while moving around make a difference?

2) If I am reading the same sajdah aayah in madrasah in the same classroom but at different spots, then how many sajdahs do I have to make?