I got a message on my phone 10 minutes ago that my order will be ready to pick up tomorrow morning (will get a new message).
If you want to watch the game early since it released in Japan yesterday and several French/German stores violated the release date, go ahead:
http://www.twitch.tv/directory/game/Mario Kart 8
Regarding Unlocks, completing Cups in single on multiplayer will unlock random characters. The more coins you collect while racing the more extra customizations will unlock. Essentially play the game, don't suck, and you will unlock things.
Also important feature, if you have a friend or sibling at home then no need to be stuck playing split screen with computer controlled opponents. You can BOTH join in split screen + online!!!
And apparently this is how online lobbies look right now....