The fan fits nicely and isn't super obtrusive. Its power wires go through one of the cut-out slots and will be connected to a detachable plug.

I also drilled some holes through the RPi board itself (Where the USB ports used to be) to allow air to flow out from underneath. There is a strip of adhesive foam on the back cover which stops air from taking the easy path straight across to the opposite ventilation holes, forcing it to flow underneath the RPi where the CPU & heatsink is.