Lots of pictures, and I couldn't get to all of them, but my opinion is that it's engine oil, which always migrates backwards. There are also some green spots on the oil pan, which could be coolant (if you're using the wrong kind of coolant - it should be the orange MB type). Oil leaks are frequently troublesome to track down for exactly that reason - the oil gets blown all over the place.
Anyway, yes, MB's develop oil leaks. One of the favorite spots for older models is at the head gasket.