alright.. Verdict is in ... Mazda is going to cover 80% of the repair, which is about $600, so I will have to pay $120 out of pocket.. I'll take it. Not worth my time and energy to fight for the additional 20%. The rep also told me that had I gotten them to cover it 100% out of warranty, if the new part is defective, Mazda would not be responsible, so by having me pay the 20%, there is a warranty on the new part. Sounds strange. I know.
I still haven't received any information has to how the thermostat differs from the control valve..