No, You Cannot use it in B&W.
It has been neither confirmed nor denied, though if you cannot then you can probably trade Pokemon over to HeartGold and SoulSilver to transfer onto it. There have been no announcements of the Pokewalker to be included with Pokemon Black and White. Since Pokemon Black and White feature new Pokemon, not obtainable in HeartGold or SoulSilver, then the chances of the Pokewalker being compatible with Pokemon Black and White is low. The only other solution is for Nintendo to make a new Pokewalker device to work along side Pokemon Black and White.
I don't believe you can get Keldeo on the pokewalker because the pokewalker is for Heartgold and Soulsilver which is only the Kanto-Johto reigon (Mostly johto.). At the time Heartgold and SoulSilver was released in 2010, very few even heard of black and white, and none of keldeo. Basically, you DON'T get it on the pokewalker, it isn't possible to get keldeo at all unless you can somehow trade from a black and white 2 from japan which is very unlikely.
No, the Pokewalker accessory is only for Pokemon Heartgold and Soulsilver versions. Though you can use the Global Link for similar in-game purposes.
No.
Yes,you must use the Pokewalker when you're not playing both games.
Anywhere, anytime. As long as your pokewalker is motion, it will gain points.
No. Pokewalker is currently ONLY available/compatible with Pokemon Soul Silver/Heart Gold.
Unfortunately, no. You can only use the pokewalker with Heart Gold and Soul Silver.
the layers are white because black is white and white people use to be black now they are white
The term for the use of only black and white in art is called "monochrome."
It means the pokewalker is registered to another game already and you cannot use it. Only one pokewalker per game, no sharing.
On the Main Screen go down to connect to pokewalker,and on the pokewalker press connect.Before you do that put them down on a hard surface,press the button then don't touch them until the transfer is complet.