I have KS 3.0 in my A1200, and run WB 3.1 on it just fine.
I got the other one with a 3.1 CPU card, not sure how much difference that makes though.
As for the battery... he CLAIMS that most of them work fine. There are a few where he says they don't work, so, I figure an ebay scammer would try claiming they all work great. We'll see.