Because of the Celebi event, it should. You just use the Union Room. No friend codes or wi-fi connection required! ;)
Pokemon HeartGold can communicate with all the DS Pokemon games. :c)
Yes.
No, but you can import Platinum Pokemon to Black.
yes
you can transfer Pokemon from Pokemon platinum to black and white but you can't trade from black to platinum
You can never trade Pokemon from Black to Platinum, because Generation V Pokemon do not appear in Platinum or any other game before Black and White. However, you an transfer Pokemon from Platinum to Black after you beat the game.
Yes.
You can't, you only can transfer Pokemon Platinum Pokemon to Black and White. I repeat, YOU CAN'T.
no you cannot't trade Pokemon from Pokemon black to Pokemon platinum or any past games.
No, but you can transfer from platinum to black or white using poketransfer of relocater.
No, there is no data of Pokemon black or white in Pokemon platinum so it won't know about any of the pokemon.
No