For the fan, this is what I used:
40A MaxiFuse close to the battery
thick wiring (cant remember if it was 8G, but I think it was)
35A Bosch relay
I wired the fan to the low speed side of the fan
In my case, i used a 3 position switch, so that I have ON, OFF or AUTO, in which AUTO activates the Delta Current Control box which controls the fan speed according to radiator temperature (and turns the fan in slow speed when I turn the fan on). The box is connected to the HIGH speed side of the fan, so there is no interference from the relay.
Felipe