1. Yes.
2. If they re-download the license file, it should have the new name, not sure though. Even if the name doesn’t update itself in the license file, there will always be the item ID that doesn’t change.
3. Changing your track name might have an influence on your sales, positive or negative influence determined by the new and old name. If the old name wasn’t search-engine friendly and the new one is, then your sales would probably go up, if the old one was and the new isn’t, then your sales might go down.