RE: Fresh air vents
Depends on the year.  '88 (IIRC) on the fresh air vent goes through
the heater core, prior years fresh air was just that, fresh air
without heat, good in summer, bad in winter if the seals had
deteriorated.  My '85 was great, plenty of fresh air when needed
through the vents.  My '90 provides little air w/o the fan on but it
is nice to get warm air from that source in the winter.  I'd rather
have the pre-88 setup most of the time.  I've never explored the
possibility of rerouting the air in the '90 but I understand the air
plenum is different on later models.