Just make sure you don't view your male profile as your female profile, or get too many connections that are similar before you're completely out. Once you do, FB starts recommending your profile to people to add as a friend. So someone you aren't ready to tell may find out indirectly.
Can't really recommend any groups. I moderate a few bottom surgery related groups on FB, but that is about it. The social ones seem to have too much drama for my taste.