I'm pretty sure best buy wants you to be mecp before you come in. As far as starting wages, last I heard it was 9-12 because they don't have a bonus program... don't worry about taking cars apart, I can't remember the last time I had to look up how to.
As for as knowing remote starts/alarms, not a clue if they will look down at that. I know at CC they don't, because it's "train as you go"... funny I'm the one training installers and I'm only 20.
Also be ready for corporate hell, it's alot different than you would think. It's not just working on cars, it's hitting your numbers, and if not having to answer to management that knows nothing about your department.