These cars came with a space saver tire and an electric pump to fill the tire. You can get keys from the dealer and coded, etc.. (I assume you have KG)
Is the car a CPO'd car with an extended warranty from a MB dealership? They should have provided you with everything. If you got it from a non-MB dealership or private sale, you might want to consider an ELW warranty from MBUSA providing it still has some factory warranty left (once expired you can't buy the ELW unless you get the car CPO'd and then buy an extended CPO warranty.) These cars are expensive to fix. Maintenance is relatively high and a brake job alone is close to $3k from the dealer. If you're not a DIYer, and are living warranty-free, then you might want to find a good Indy. But if you've owned a Jaguar, then you're no neophyte to all this.
If you can convince a MB dealership to run the car's VMI for you, then you'll have a record of its service history (providing it was serviced in the dealership network.)
Known issues are camshaft sensors, camshaft adjusters (if the car has a noisy valve train sound to it), Airmatic strut failures, and fuel sending unit leaks (gas smell and leak under the rear passenger seat.) They also eat rear tires. If you drive all the time in Sport II mode with the Airmatic, you will introduce more negative camber and the inside edge of the tires will wear faster. Otherwise the cars are fairly solid when properly maintained.
Wipers you can get anywhere, but don't pull the wiper arms straight out from the windshield like you would on other cars (e.g., when you are cleaning the glass with a squeegee.) Be sure to turn on the wipers and shut them off first when they are about 1/3 down from receding into the cowl. Then you can pull them out. Otherwise you will scrape the paint. The owners manual has a diagram showing this procedure. No big deal, but it will look crappy over time with paint and clear coat scratched off the hood cowl. (btw, the hood itself has a service mode where you can raise it 90 degrees and access the engine bay much easier.)
Several online OEM parts vendors are around. One is MB Online Parts
which is a sponsor here.
Owner's manuals and the service books are available free on line from MBUSA. The COMAND (nav, etc.) manual is available on line (but not from MBUSA.) If you want a full pdf copy of both, pm me and I'll email them to you.