Done. Now only moderators, Donators, and VIP members can change their names automatically. Other members should contact me. I'll probably ignore your request if you have less than 50 posts (unless your posts are very good).
You can't. You can try PM an admin and they may do it, but they usually don't. You can just create another account with that name if you feel like you need it.
If you are not VIP or Donator member, you can not change your username.
Admin can change your username without VIP or donator member condition if he sees you have good reasons for your privacy, dox or something dangerous to you.