Re: su not asking for password
I'm guessing this is a rawhide issue. It shouldn't happen. In most distributions, where there is no root password set, the only way to get root is to do sudo su, and then, assuming you're in a group allowed to do ALL on sudo, you are able to su.
However, if no root password is set, then su by itself shouldn't work.
If this is the case, I would guess it's a bug.
I just tried in console on freshly updated F18 (though this is beta rather than rawhide per se) and that wasn't the case, if I typed su it required the root password.
One thing though. If you do sudo su -c <command> and then do it again within 5 minutes or so, it won't ask for a password the second time. In that case, however, it requires the user's, rather than root's, password.