he will at least ask you out or make a lot of efforts to be really close to you.
sure he could be rebounding or just bored, especially when he's young. as a guy gets older I think he is more likely to think carefully before committing to someone. when you are young teens it's more of a game.
Depends on the guy, some are shy and never let the girl know how he feels about her, so I would guess the others would ask the girl out. Sadly, some people are rebound gf/bfs, so yeah guys/girls do that.