Hi Raffe,
1. Might be wrong, but part number 17118666838 (link) might be an indicator. I assume that there is no distinction between the protection of the normal version and the M Technik option.
2. 18" Doppelspeiche 790M should fit, too
3. Difficult to answer. The brakes on my former F30 340i use to squeak, the brakes on my G21 m340 did not. The latter is also true for my 2Ms. Generally speaking: ceramics tend to present a higher squeaking probability. For the steel versions, I would say that it mainly depends on your driving style and the amount of time that car stands still. The less you brakes and the longer the car stands, the more they tend to squeak.