1) Make sure you are using the correct weight oil (10w30 won't work,
unless you are in North in Winter).  Make sure you are using the right
oil filter.
2) This could be the idle stablizer control unit. It's a $200 relay in
front (behind) the right rear tail light. If you've a Bentley manual,
follow the procedures to verify if your idle is working correctly.
3) The Radiator Fan normally has a couple of speeds. One you won't hear
from inside the cabin normally. The high speed you can't mistake.

A heavily laden (this isn't hard to get to with a Westy) Vanagon will
really work hard (i.e get hot) when climbing steep grades (at least in
MY experience). You shouldn't have a problem on flat land, if you do,
then you may have other coolant problems (clogged radiator?) Note that
out in the West, it isn't always obvious when you are on a grade,
especially if there isn't anything around for reference.