Does this guy like me? Any ways to tell if he's gay or anything? Like clues?

[Nonya1]

Ok. so ive just started college and ive been having a few crushes lately. There is this one guy who is in 4 out of 5 of my classes! Well yesterday me and my friend were walking to our next class and I held the door open for him (I had to stay there a few extra seconds, but I was just being nice). So after he got out of the building me him and my friend started talking small talk. that kind of stuff. So we departed and I headed off. well when i got home and checked facebook, he had friend requested me. this is when I started to think somethin was up. ok so i accepted it, and later that night somehow we started chatting on there about buying books and stuff. and i mentioned we should study together since we have almost all classes together! he agreed. so got to school and we walked to class together. our classes are from morning till like 2, so we cant eat anything. we both said how we were starving and he said he was going to burger king. I had to go home to get ready for work, so I couldnt. But I think that was an invitation for me to eat with him? idk. so any ideas? I will end up not doing anything out of the ordinary, just act normal and try and hang out. I just want to know if yall think hes gay/bi from what ive said, u dont know? I'm just trying to fill him out. thank ya!
I know its a ton to read, but I like to give background to get better answers. sorry bout the length though!
ha, i dont think I could just ask if he was gay! I dont want to make things awkward. hes in almost every one of my classes! if something happened, it wouldnt turn out right. ha, I dont have the balls for that one!
thanks everyone! these answers are really helping me out! I like to hear what other people think of a situation, so I dont over analyze it or anything! thanks everyone