1. Watch Ebay - they show up decently often there 
lately. (Backgrounds alone don't show up on Yahoo 
Japan very much.) You can also find them at Taro 
and there are a couple other cel shops that have 
carried them from time to time. Basically, keep 
your eyes on the "usual suspects". ^_^

2. Once the background has been separated from 
the cel? Two words: "very" "slim". ^_^;;

Many Sharp Smiles,
--Drac