-A PC fan will be dead in days because it is far from weatherproof. oyea, and 15 cfm it'll move is worthless above 1 mph.
-mount the trans cooler before and in line with the factory in-radiator cooler only IF NEEDED. Keep in mind your transmission is fine unless you're doing lots of towing or up steep hills...high load conditions like that and the transmission fluid does need to be around operating coolant temperatures to be at it's best: it's engineered that way.
-if your radiator cooler is set up like mine and runs the trans fluid through a tube in the radiator (helps heat up and keep from overheating) it will be moderated by the coolant. unless your coolant starts overheating massively, the trans fluid won't overheat either. that is unless as stated above, you do lots of up-hill towing or drag racing.
-in-line pump: DON'T. during normal operation (any time not in park) the rotation of the torque converter connected to the engine spins the pump in the transmission. adding another pump in-line will do one of two things: block flow (bad) or cavitate if it's powerful enough. (less bad but wasting the power to spin it) and you'll have a hell of a time matching it to the pump in the transmission (changes with engine rpm. same problem as electric superchargers)
1991 Toyota Pickup 22R-E 2.4 I4/5 speed
1990 Toyota Cressida 7M-GE 3.0 I6/5-speed manual
mechanic, carpenter, stagehand, rigger, and know-it-all smartass
"You don't get to judge me for how I fix what you break"