On top of these other recommendations, I would get a trans temp gauge, It's pretty easy to keep the engine inside a good operating temp range and still smoke the trans. Don't ask me how I know that one....
Yep. I have monitored mine with a scan tool. The trick is to try to keep the converter locked.
A short time unlocked is fine, but if I am going to be pulling a hill for a long time, I will back off the throttle until the convertor locks back up again. The temps always stay stable if the converter is locked up.
I have the factory external trans cooler (which the OP's 2500 should also have), but a bigger one is on my short list of things to add.
There is a good writeup on swapping in a almost bolt in larger cooler in place of the factory one on this site.