Thank you very much, @StacJip ! That’s all very helpful, and I’m very sure that the willingness to say “Yes” is worth a lot in the music world!
What?!! Your son prefers playing and teaching music to putting expensive coffee drinks together for picky people?! That’s crazy talk! 
I’ve actually told him that he’ll have a MUCH better time if he can figure out how to go out and do some gigs during the summer, rather than flipping burgers (or lattes).
Fortunately, he’s already a very good writer (point of pride with me, as I’m a writer!), so we’re good there.
Right now he’s just really, unexpectedly nervous about the changes entailed in going off to his new life. I’m ashamed to say that it took me by surprise; I thought he’d be nothing but thrilled when he got his acceptance to the New School, but that was a little dense of me. I know he’ll be fine, but it’s a reminder that things are never quite as simple as they seem to be.
Your son sounds as if he’s been doing amazing things!