I know we come from very different cultures and I have no intention of judging you, but can you perhaps give me a clue as to how this would work? I'm intrigued, to say the least.

proposed = asking for a date or if he's too forward / self-centered then asking her to "be my girlfriend"

crush = a girl I like but haven't told that to her or shown it in public

And yes for kids in school it's quite common to initiate conversations through mutual friends because otherwise gossip spreads too quick and can sometimes be damaging (both emotionally and socially).