As do we~
In regards to your questions, we would be looking for a pretty decent match to the colouring style. The cg artist said they would share all the needed info about their brushes and detail how they colour so you won't have to figure it out for yourself or anything like that. It would just be for CGs. Sprites are fine since they are a smaller doc and don't cause the artists computer to crash.
But hey if you want to try your hand at making BGs then we still have that position open. [nudge nudge]