@3 - I believe "su" is a reference to the unix/linux command "su", which when executed on the command line gives "SuperUser" privileges (AKA root privileges ) to the executor until a request is made to stop executing as root. "sudo" is a related command that executes whatever it's followed by with root privileges. Hilarious "sudo" related nerd comic: http://xkcd.com/149/
@5, though that's not what "su" does. All it does is "substitute user", giving you a new shell with whatever privileges the new user has, from within your own shell. This could be more privileges or less. "su root" is how you would take over as root on a machine from your own, hopefully less powerful, account (after supplying the root password, of course).
Opening text massaging app on the iPhone and typing "grill warmup" and "grill hot dogs": 30 actions
Turning on the George Foreman Grill: 1 action
NERD!!!!!
Wow. Cool.
What if it freaks out?