The problem with the drifting might be a loose/bent balljoint or some kind of screwed up bushing that got damaged in the accident. The bushing holding the rack might be a bit loose as well. Accelerating usually puts stress on the loose/wornout part causing the car to wander to one side all of a sudden. Best thing to do is get the car up on stands and visually check everything, make sure the bushings aren't cracked, and check the joints for excessive play.
As for the turn signals, there's a disk that turns with the steering wheel that "kicks" the signal lever back when returning the wheel after the turn. If they didn't align the disk properly with the steering wheel after removing the steering wheel (which is something I've done myself), that would cause the problems you're describing.
