[John_AZ]

Hi Bob,
I'll just comment on Q1.

The fans, thermostat, fan switch in radiator and the coolant temp sender in the block are related. The car needs to get to a specific temp to be efficient. The coolant temp sender in the block sends a signal to the DME computer at proper temp. I am sure hooking up both fans is completely possible and should keep engine temp down. I do not know what would happen to performance and mileage.

When you turn off the switch and leave the car, the fan(s) say on until the radiator fan switch gets to the low temp.
If both fans are connected, the battery will discharge. You may have to compensate with a different radiator fan switch temp to avoid the battery from dying completely.

GL
John_AZ