Glad to hear you got some/most of it sorted. The heater rads tend to be just inside the bulkhead, under the dash. Because of this positioning, sometimes you get water building up in the footwells of the car - check under any car-mats you may have, just in case it's hiding on you
Heater rad went on my Ford Sierra (same as the Merkur in the States) and I bypassed it at the side of the road using a Swiss Army penknife
great inventions!!
Coolant in my car flows from the header bottle (coolant tank thingy) into the heater rad, then out of the rad into the block. From the block to the main rad and then from there, back into the top of the header bottle. Not sure if Jeep coolant systems are the same or similar but it should be fairly easy to trace it.
