from other forum:
oh...from other forum:
The fan is a large attic ventilation fan near the ridge of the roof. The roof has two gable vents on either end and lots of small round soffit vents.

pav probably doesn't come on in winter..depends on what it is set to.
but it will...when operating... depressurize the attic. exacerbates duct/return
leaks and leaks from attic into house...the one (yay!) recessed light, the
oversized cuts at bath fans..and top plate leaks.
disable the pav & when you replace it, use passive vents.

and remember..this is a hole in the roof...air in...air out.

I hear you about the gaskets...but the way to stop the leak comming out
of the slots for plugs. baby proof things you put in outlets to keep kids from
sticking stuff in the outlets. put the piece of foam gasket that you usually
throw away on the baby proof plug & put it in the outlet.
thats a Zero Draft tip btw. (credit where it is due)

interesting reading between both forums.
questions are really flowing now!!

as for some local companies for pricing. if you can measure roof sq ft
(or even if you can't) they can give you a sq ft pricing. estimates are usually free.

best of luck.