1999 Mercedes Benz CLK320 OBD2 code P0700 and "Maint.

I get the transmission controller error (P0700) when I plug in my tester; how much should this cost to fix (about)? The car runs GREAT, and there are no signs of slipping, missing, or grinding gears when driving (at ANY speed. Any LEGAL speed, of course. Yeah, that's what I meant.). I had to drop the tranny to replace the controller on my Jeep; can this be fixed in the 'Benz through the onboard computer (without wrenches)?

Also, the 'maintenance required now' light just came on (no P-code), and I need to know what to expect the dealer to do (oil/lube/plugs/coolant?), And how much to pay. I bought this car last week (from a private party; he'd only owned if for a few months), and I don't know what work has been done in the past five years (I got the older records). I'm a Nuclear Design Engineer (and shade-tree mechanic), but this is my first 'Benz; I wouldn't fall for the, ". You need to lube and rotate your thermal differentials.", But I probably wouldn't know if they didn't do what's expected, either.

Yeah, I expect to pay handsomely for Certified Technicians, but within reason (and I don't know what's reasonable).

THANK YOU!
Jim