1. Owner's manual is pretty good.
2. The maintenance CD is also good. This is generally available on ebay for about $10, although it is not a legal copy and is a PITA to use. What I did is get that and print out the relevant sections on the laser printer at work. Punched holes in the pages and made a manual myself. My misgivings about using illegal copyrighted material were assuaged by the outrageous prices Mercedes charges for the legal approach - really a bull**** company when it comes to sharing technical information.