Ban permissions and username/email banning.

Can you add a new permission to allow/disallow a moderator from using the ban option?

Also, from looking at the code, the ban seems to go a bit overboard. It currently adds the user's email and username to the block list as well as disable their account, when the disabling of the account should take care of both (users cannot register using an already registered name and email, even from blocked accounts).
With the current system, what happens if an administrator removes the ban later on? The server will still have the email and username block, but with a user who is actively using both. It might cause confusion, such as in the case if the user changes their username or email to something else, then wants to change it back.