I believe the saying is "never spit into the WIND".
Some dealers are good, i don't see that coming into play just yet or relating to his problem.

The long time in warming up, and the one time it seemed to have a high temp reading, may be caused by a bad engine thermostat.

All the other problems (plus possibly also the one time the engine ran hot) may be caused by the auxillary cooling fan problem.
I'd get the aux fan problem sorted out, find out what works and what doesn't work and troubleshoot that, and see if they want to diagnose the slow warm up, or just ask them to replace the t-stat.


Gilly