Moved to hardware/equipment forum:
I'd run some water through it before using it on the tank but other then that you shouldn't have to do anything special. Chillers can be placed on the ground or at the tank level it isn't going to affect performance but some can be noisy so you may want to keep it under the tank.
Yes you want to run it from your return line then to the tank, make sure your GPH
are within specs.