I love this game. I don't know how to play with friends, other than sending a friend request. You can then PM a friend if they're online and set up a locked game. But playing with strangers is fun enough.
My End of 2008 Hardware Predictions (console only):
Wii : 50 million
360: 28 million
PS3: 24 million
These predictions were made on January 3rd and won't be revised