A few questions and thoughtas about the Riggins' and Riggins Rigs

I just finished the show!

1. Whatever happened with Riggins Rigs? They mention it's still going but we never see it in season 5 and Tim doesn't go back to work there. I thought when he got out, they would make him a partner. Is he not allowed to fix cars anymore or something? I always saw Tim as the small Dillon business owner type...like Riggins Rigs or a bar like Buddy.

2. Related to Riggins Rigs: why did Billy act like the coaching job was a source of income by the end? I thought it was volunteer.

3. Tim tells Tyra he will never do anything illegal again. Then he cracks open a beer. lol. Is he 21? I guess I figured he probably was since he worked at a bar and timing wise, 20-21 seems about right. He should probably not serve Julie and Saracen alcohol at the bar for a while. heh.

4. Tim tells Tyra he had nothing to do with the Chop Shop. He was not the lead on it, I'll give him that but I'd hardly say that he was fully innocent.