Don't know much about your C280, but try looking for the oil filter on the left (driver's) side of the engine. It may be near the dipstick and under a cover.
As for the manual, it is on a cd-rom. I don't know if i is available for your car yet. I have heard that if you call the Mercedes toll free customer support line, you can get it on microfiche.
As for the manual, it is on a cd-rom. I don't know if i is available for your car yet. I have heard that if you call the Mercedes toll free customer support line, you can get it on microfiche.