It is possible that the heat created in the transmission can drive the coolant temp up if you have the stock cooler still in the radiator, but the heat would have to be pretty extreme. Have you checked the fluid condition? Color and odor will tell the story on excessive heat.
It is possible to have the converter howl like that. Putting the transmission in neutral will take some load off of the converter. The slippage is a sure sign of some sort of failure, converter or something else. Best to pull it and find out what, ASAP, before more damage is done.