You can only buy it online. But you can play the maps offline there after.
Yes
Once you are on the Black Ops multiplayer screen go to store and you will see the First Strike map pack for 15 Dollars.
Ascension is the only zombie map in First Strike
march 3rd
March Third
14.95 $ USD
March 1,2011
you cant
The first strike map pack cost $15.00
First Strike
You need to buy Black Ops Limited edition and get the free First Strike Map Pack or if you already have Black Ops you need to purchase the $15 First Strike Map Pack at the Playstation Store
You can not get the new First strike Map Pack for the Nintendo Wii Call of Duty Black Ops