Doesn't the car have the maintenance booklet in the glovebox? It's normally stored in there with the owners manual. My E-class has a leather bound holder for the whole set of manuals & booklets.
You're probably due for a B-service. About 12K miles is a typical change interval. If the car was serviced at an MB dealer (which it probably was) they'll be able to lookup the service and warranty history. The first service (an A-service) was almost certainly performed at the dealer - it's a freebie, even before MBNA started including routine servicing during the warranty period.
Does this car come with service included, or did that start after the '99 model year?
FYI, on my E-class an A-service is about $150, a B-service about $300. The two just alternate. I expect prices are similar for your car. Other than that, the coolant should be changed every three years (i.e. now), and the brake fluid every two years. (Probably past due - most oweners don't follow this requirement.)