Assertive which is firm but reassuring, clear but concise. It's the best way to set boundaries with friends, also give the guy a hug or kiss on the cheek, he earned it with the good book choices.
Nothing, we are the noobs, we need to adjust to our elders. He's creepy more cause we don't understand than anything he's trying to do. If he wants to help us to be less creeped out he can teach us more about himself and his time at crying rock.
Choir, a battle tune can turn the tide. Public speaking, a skilled orator can turn shapeless rage into a weapon of passion. Computers cause Alex can help with our homework!