Are you guys good enough friends to where you can admit it without him getting upset? If so, confide in him and if not then try to let it play out and see if he might feel the same way. He could be completely straight, and if that's the case then you'll just have to accept that.
Ah, it's hard to say. There are times when I've been hopeful about women liking me and I'm completely wrong so it could be you being hopeful and that's where the vibe is coming from, or he could have genuine feelings that he's not coming to terms with. You never know he could even like that girl you're talking about... or not. I'd remain friends for now and see how it plays out. If you're not too familiar with one another saying something could freak him out, even if he is interested. Ya know, not coming to terms with feelings and all.
That sounds like a good plan, as it let's things play out more naturally. Well, good luck! Hopefully things turn out in your favor.
dont be naive