Post #3 and #6 make more sense to me than spending all that money on a powered attic ventilator.
It is said that when something pulls air from the attic, it must come from somewhere and often that somewhere is the conditioned air inside your home. There are many air leaks into the attic from inside. Attic ventilation is designed to pull air from the soffit vents into the attic and out the ridge vent at the peak of the roof and the static vents placed fairly high in the attic roof.
You might be better served to do some air sealing and add a couple of static vents if you feel that it's necessary (for whatever reason.) but more roof penetrations are not always a good idea.
Here's a quick video... there are loads more on Youtube on this subject.
Don’t Let Your Attic Suck - Power Attic Ventilators Are a Bad Idea - Energy Vanguard