It was confirmed by unreliable source. (Nintendo Rep. I'm not sure if it's Treehouse worker or not)
I'm pretty sure there will be, though perhaps the Wii U version might not because of the 3DS version (I doubt this though).
Yeah, I'm pretty sure there will be too. I just hope that none of the ones revealed so far (unlikely as it is) are hidden.
Granted I wasn't able to survive the spoiler mine for the month between Brawl's Japanese and American releases, so I probably wouldn't be able to stop myself from looking at them again with Smash 3DS even if Nintendo didn't spoil all the unlockables.