So with the option key down, both of those choices happen without any additional dialogs or delays. You can also see the shortcut for the immediate logout when you're holding the option key down: pressing shift-command-option-Q will result in an immediate logout.
Addendum: After publishing the original hint above, an anonymous tipster submitted these keyboard shortcuts: "You can use Control-Command and the eject (or F12) key for an immediate restart, Option-Command and the eject (F12) key for sleep mode, and Control-Option-Command and eject (F12) for shutdown."

