Electric fan

Definitely run it off a relay. The secondary fuse block is a great idea.

Unfortunately with mopars fantastic approach to wiring the charging system, please not sarcasm..., There is no perfect place to pull power with an item that may run in both engine on and off configurations.

If you have a wire around set up in place, I'd tend to run the power off the alternator. The alternator powers the car with your engine running and most likely when the fan will be running.