I'll answer your last question first...I think that my homosexuality played a huge role in my experience, from the get-go. But that was because I grew up in the late-80s and early-90s, where being gay was a popular taboo throughout most of society. Whether I was a gay boy who wanted to be valued, or a bi boy or straight boy who was perceived as too "effeminate," what I endured was due to a combination of misogyny, misandry, and homomisia. It was baked in -- and even if I'd been an actual heterosexual kid, I most likely would have been "mistaken as gay" (and still suffered the ramifications of it).

I do agree with you that one benefit of being in a coed school, for me, was that a certain segment of girls who were my classmates openly felt comfortable around me (presumably because they noticed I wasn't being crude and predatory in the way so many other boys were behaving). There were also some nice boys who at least showed me modest acts of kindness, from time to time. But the amount of male bullies and female bullies who targeted me were about equal in number to one another. So, in that respect, it could be more of a testament to how the schools I attended didn't have strong (or consistent) enough anti-bullying policies.

So your first point is quite succinct: it really depends on the school. And too many schools are comfortable with their delusion that the status quo is just fine and dandy for students across the board.