I'm pretty sure hes giving you signs, telling you that hes interested. If not, then he just really really really cares about you.
Well for me, what I look for in a guy is for him to actually like me if we do date. But the guy has to have a good personality, doesn't act like a jerk in front or to girls. Funny, cute, sporty...etc
Theres no problem in being in love with your best guy friend, since hes been there for you through the thick and thins and you guys known each other for a while right? I'd say you should slowing start showing him some signs that your starting to like him and stuff.
If they do, that means they like them.