I don’t know the answers to your questions, but might offer some insight.
Like many straight people, I can’t really even imagine feeling attracted to the same sex (male in my case). This, to me, is the best argument that the “the gay” is NOT a choice. I think most homosexuals had exactly as much choice in the matter of gender preference as I did: exactly none. Which kind of speaks to your first point: Homosexuals are attracted to the same sex for exactly the same reason that heterosexuals are attracted to the opposite sex: Because that is the way they are wired.
To your second point: I myself ( a straight male, recall) am most attracted to “Butch-ish” women…or at least “Tomboy” types. Rachael Maddow, or maybe Ellen DeGeneres, only straight, and with red hair would be about what I would come up with if I were allowed to design the ideal woman for me. (Yes, I realize neither are very far up the “butch scale”)
Now there are many men, even straight ones, who are a lot more ‘fem’ than either of these ladies. Yet they hold zero, or even less than zero appeal for me.
It may be just knowing they are men. A few months ago a met a person who was either a fairly fem guy, or a fairly butch woman, and I really wasn’t sure which.(I posted about it somewhere on the board, can’t be bothered to search) I was attracted, but more so when I found out they were, in fact, a woman. If I had found out they were male, it would have been a total turn-off, I am pretty sure.
This isn’t about wanting to “convert” lesbians, nor join a threesome. The only time I have ever “hit on” a lesbian, it was without knowing ahead of time. I am not interested in changing them, and don’t really need the extra reason to be shot down. Still, they get me hot and bothered. There is just a certain type that attracts me, and about 90% of that type are lesbians. Thank Og for that other 10%.
All that said, I don’t require exactly this in a mate. I have dated some very “girly” women, and find things about them to enjoy. Just any time I see a female basketball player walk by, it is going to turn my head.