I'd almost have to see the mirror problem to know what they're talking about, but you're not the first with a loose mirror plate. Sounds like just the wire bale is missing.
The parking light has always been a big 210 problem up to 98 or 99. There is a service information bulletin about retrofitting a newer style socket, should NOT be a big deal and the dealer should know about it. Possibly they could do it for free, unsure if this was a service campaign or not, if it is, should be covered by MB, possibly they can't since you aren't the original owner, but even then I'd bet they could if they wanted.
ps Maybe Dr D or ILUVMILs can check out to see if the parking light socket updates were a service campaign or not.