@evilmorin3,
1) what the hell dude? don't penetrate anything. (you realize that that scene from American Pie was a satiric comedy, right?)
2) As a matter of fact, vagina is better than butthole but this is beside the point. Sex is much more than penetration, and if you find the right partner, you won't miss anything. gender plays no role in it.
3) Yes. Usually nobody cares, so if you don't tell people or act weird people won't notice.
4) This is a bit more complicated. Many gays use social networks, dating gay sites where is very easy to figure out who is gay/bi and what does he seek. Or you can try gay places like pubs or discos. High school might not be the best place for search for a partner.