just making sure
havent gotten any back to 100 yet so just asking
since its described as 'basically eliminating the level cap' i assume you can do it multiple times on a skill, but just want someone to confirm

There's no limit as to how many times you can do it.

If you're looking for fast exp, I recommend pick-pocketing. Just crouch behind a carriage driver, plant some gold and steal it back.

Yes, yes you can

Yes.