No word on song export for RB2, but they've "promised" anyway. And anyone who redeemed the code for the 20 free songs has already "proven" ownership of the original game, so all they need to do is charge those people the export fee.
As for the Wii? I don't think that'll happen. Yeah, you can drop a 32 gig card into the Wii, but I just assume they didn't plan for anything like that.