Welcome to the world of watercooled!  You are experiencing normal conditions.
 Actually your engine will run best at operating temperature (which is where
it is right now).  If you try to make it run alot cooler you will start to
actually lose performance and gas mileage.  This is not an air cooled where
you are struggling to get it as cool as possible in order for it not to
explode.  It is a water cooled and right now everything is working as it
should.  If you want to close the valve under the rear seat that is fine, it
just shuts of the rear core in the summer (you actually have heat now!!!).  
As for the valve in the engine compartment this should be closed (turned in
all the way) as this is just for bleeding when refilling coolant.  Hope you
enjoy your van.

Thanks,
Ken Wilford
John 3:16
www.vanagain.com
Phone: (856)-765-1583
Fax: (856)-327-2242