For bans, in the ACP check under User Admin->Ban Control.
Once posts have been deleted they're gone. Unless you have a backup of the database there's no way to restore the posts.
As for the user activation, set it to "Admin" (ACP->General Admin->Configuration->Enable account activation (None, User, Admin)) in order to have an email sent to all administrators in order to activate accounts.
Just for fun, I'll sometimes merge two totally unrelated topics.