On the money thing, I’ve always liked the idea that I take some of the adult kids money and store it away for them for when they move out.
My kids are far too young for that, but I don’t think a bit of that sort of thing hurts in the long run. He’s earning significantly more than I was at his age and he’s not paying much at all; I’d give £150 a month to live at home 15 years ago, and I never saw any of it back.
Charge him board. It’ll benefit him in the long run, especially if you fence off some of that money to give him later.