Well it sounds like a lot of the playful, flirty things people do to show they like each other- he already does and with all his girl mates, so anything subtle like that isn't going to let him know. I can completely understand why you'd be reluctant to come right out and say you like him, but suggesting the two of you hung out alone one night would allow him to say yes if he's interested, but let you down gently if he's not. It is scary, but you have to put yourself out there a little bit or you'll never know. Personally I wouldn't involve anyone else in the group as that can just make everything harder if he only sees you as a friend. If he is as nice and considerate as you say, then I'm sure he'll handle everything like a gent!
Thought he was 19... really he's 14