My 350SDL had every screw loose on the side of the IP when I bought it. Tightened 'em up, never another issue (well maybe a tiny bit from the "O" ring on the stop lever).

Can't see from the pics if the injector return lines were replaced...notorious leakers.

X2 on the oil leak...it seems up high (and running downward), so the breather(?) and/or valve cover gasket(?)

Looks like no one was caring for the car for a while. Did you check the dipstick to see if anyone cared enough to replace the leaking oil?

FWIW, why are you talking with a dealer (even for someone else)? Do they have service records with the car? Man I hate dealers.....