Cool, yeah, I run those gauges, too. PITA user interface, but they work and look decent.
Keep in mind the stock temp sensor is somewhere in the transmission (sorry, can't remember where off the top of my head...it's on the side of the case but where in the flow I can't recall). Anyway, you'll have two temps to watch: temp in the oil galley, and temp at the cooler (mainly this is the temp as it's sent out from the transmission, so at its hottest). My case sensor always reads a good bit below the temp at the cooler, so my guess is it's earlier in the plumbing.
When I first got it and it was fully stock, it would get to 200 no problem, racing or just annoying the floorplate. After that, and a built transmission and TC, I run a custom cooler. Turned the stock auto cooler into a cooler for the steering pump.
In my experience, I'd only stick with the Motorcraft specified fluid. I tried running RP and other brands for a time, and had nothing but issues. I get all the "it's the same" chatter, but hasn't been my experience.