1: No... although the approval system is supposed to be getting a pretty hefty update sometime in the, hopefully near, future. Currently, when someone first submits, they show up on the Audio Mods approval list, and we look it over to make sure it doesn't break any rules. If it's clean, we approve the account, and you don't have to go through the process again. If not... well.. we ban the user and they have to make a new account and try again.
2: You don't. The delete button didn't make it into the redesign in time. The only way to delete submissions currently is to have an Admin do it. An easy way is to make sure you don't upload anything you don't think you'll want to take down later in the first place.
... At least until the missing delete button is reintegrated.