There certainly is nothing stopping you from looking under the car to see if anything that looks like a brake line is touching the exhaust... better safe than sorry! I'd be looking right now if I had a M6... I can work a zip tie in the meantime, lol.
Loosen a couple nuts and slide it down... the bolts go through oversized holes (square), just be careful as it will move side to side some if you let it... though I actually had to make those holes larger with a Dremel on the S550 to get it right.
While I have not tried the drift brake so can't say for sure... (I have never thought my tires had too much rubber on them, lol). I just remembered some of the comments from the early drifting videos, that said they had to figure out how much brake to get a good drift... so maybe that only meant...
There are several adjustments.... screw the hood stops out (2 hex shaped rubber bumpers), If they don't go far enough or the hood is held up too much, then adjusting the hood latch down will take care of it. On my S650, I was able to do it with just the hood stops, on my S550, I had to adjust...
All of the suspension bushings should be "clocked" on a lowered car... With the car at ride height, loosen the bolts on the control arm bushings and sway bar bushings, then torque back to specs.
In the US, once the car has shipped the dealer is about the only way to track it. Not sure how it works in EU... If your dealer told you where it is, he's probably got the most info.