There are no stock forced induction cars that have a MAF in a place where it can come under pressure. That is how the manufacturers designed them to run.
http://www.motuk.co.uk/manual_330.htm Section A, reasons for rejection 5 "5.When the pedal is fully depressed there is not enough reserve pedal movement."
Sounds like an alternator fault. Ive seen it before where the alternator doesnt give out a charge unless it goes over a certain RPM. I think my one needed to go over 3k RPM. So if I managed to do a journey not going over that RPM the battery would drain.
The brake light switch has 2 functions: 1) Control the brake lights 2) Tell the ECU the brake is pressed Itll 2 that isnt working. I would VAG COM the car, see what the recorded error is!