1) Just comparing sizes is natural. You're probably wondering how you compare and you're curious of how the other guys are. That doesn't make you gay, because you're still like girls, right? If you do, how can you be gay?
2) It's anyone's guess whether someone "turns" gay. Who knows, you could turn out bi...but this whole thing doesn't really mean you're gay. You're just curious, and that's something that at least 95% of guys go through!
I say no worries man