Well, female fighting characters (either ones you fight as, with, or against) are certainly treated the same as male fighting characters in D&D - at least, I think so. Fighting characters are not the only type of characters in D&D, though, and on a wider overview, I don't think you could really consider that principle to stand up to any great degree...
Yup. You're character is created, not randomly sampled, so she doesn't need to represent a typical member of society. You can play a Nikki Fuller-type character if you want.