Mine is 5, just loves music and dancing so I enrolled him in a class to start in a few weeks. I was so pleased with the dance studio and the variety of classes that they have that I enrolled myself in an evening class too.
i don't think there should be differences in education btw boys and girls, because it creates sexist individuals, and sexist people are potentially dangerous (beating wives, fighting boys, etc...)
I don't think it's gay at all. In fact, there's nothing wrong with a guy dancing even into adulthood. Doesn't mean I would want him to be a professional ballet or tap dancer, but if he does it as a hobby, then I would probably support it.
If he enjoys it, then why not? It's a great way to interact with other kids too.