RE: water pump
The pump in the link will not work for you. It uses the pulse from the internal cumbustion engine to produce the pumping effect.
What you could do is buy the smallest winshield washer pump from your local auto parts or salvage yard and plumb it to a small radiator. A bilge pump used in RC boat combat may also work for you. I have seen a few radiators sold on ebay from time to time for the Conley.
You could also make a small heat exchanger to work with that electric pump. Take some small diameter tubing and coil it in a sutable water tight container that would be air cooled, fill the container with water. Then plumb the coil with water in line with the pump and whatever part you are trying to cool. The container needs to be of a material that would allow the air to cool the water alowing the transfer of heat.