I haven't tried that as I have yet to get the key off of the WFC. I guess you have to getit at a special event.
I'll test to see if Rotom changes once I get the key and trade it with my sister.
I'm going to guess they will stay because previous special pokemon and what have you from other versions were secretly included ahead of time by the developers. Mew was a secret for a good year or two before it was revealed, right?
No there are no actual new pokemon (like new numbered ones). There are 494 total, TJ Spike, I think you forgot Arceus.
Also, my sister wanted me to point out that if you got one of the Regigigas from the special D/L promo last month then if you import it to Platinum then 'something special happens'. Her mystery gift card that came with the pokemon D/L said this. We haven't sent it over to mine yet but we'll go ahead and try that today.