Answer 1

Of course. Pt and HG had same events, and that stuff. Keldeo, Meloetta, and Genesect will probably be for both versions. But B/W 2 will not have the ongoing events already in B/W.

Answer 2

http://bulbapedia.bulbagarden.net/wiki/List_of_Japanese_Nintendo_event_Pok%C3%A9mon_in_2012#Shokotan_Keldeo

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If you check this event, you will see at the bottom that it says

| B | W | B2 | W2 |

So it will be automatically for Black & WHite 2, but it could be.

Answer 3

It's the first version only ;(