That my friend sounds like a plan. Did you have someone else look at the radiator that separated? If they put it in writing it becomes pretty tough to dispute it wasn't defective or that you created the defect. What is the $100 replacement fee for, did they tell you?

 

I re-read your post about the brown snot on the pipe/hose between water pump end of engine and firewall, which leads to heater core. When you get back to working on this puppy, I suggest taking those two hoses off, and reverse flushing the heater core (heat will have to be on and turned up to high for valve to open) - bet there is more brown gunk where that came from. When engine is cold, thermostat is closed. Coolant circulates through engine, can't get past thermostat, so it takes the bypass route through the heater pipes. If they are clogged, pressure could build up. You can also bypass for testing like slanginsanjaun's PO did: