Then he started to get cocky because he was "getting involved". And now I have other people in my class expressing interest in the position. And they're good guys too, but I just never talked to them before.
So now what do I do? Obviously I'll have a small interview with both, but I expect similar results. So who do I pick? Do I pick someone equally or slightly more "qualified" for the position, or do I give the position to my friend just because I already offered it to him, and he's expecting it?
Picking someone just because they are your friend and you said you would probably pick them isn't fair to the other people wanting it and isn't fair to the society. Especially if that guy is just going to be cocky and such.
If he gets pissed at you, just explain you have to be fair. I am sure he will get his panties out of a knot after some time.