David,
   I would not be satisfied with a mechanics"opinion" on either count.
Especially since he did not hook up any test equipment to arrive at his
"conclusion".
   For the coolant spillage I would replace the pressure cap. This is a
common failure item and yours is displaying the symptoms.
   For the other problem, I highly recommend an analog oil temperature and
pressure gauge (for any VW flat four engine). The cheapest insurance you can
buy for the longevity of your engine. On long trips the oil temperature
dictates my speed. If it starts creeping up to 230 I start backing off the
gas.

Ken Lewis
1986 CrewCab; 260,000 miles on original engine
http://neksiwel.20m.com/