Chris ,There are some formulas but they are very complex.I certainly can't understand them but you just might.
I found something that might be easier to comprehend for most here:
http://www.sonnax.com/articles/90-Hi...ction-and-More
On the second part, the best non answer I can give is it might get better or it might get worse.
Generally when you soften one up by machining stators away from factory engineered profiles, you do lose a few % points of torque multiplication . But if it gets you up where there is more torque to multiply at a certain rpm, then you still will have a net gain in ET.
Personally,I haven't seen any big swing in brake stall within what one would call normal drag racing temperature ranges. Once we get to the point where the fluid starts to boil and vaporize, then we will see a loss in 60' times for sure.
I'm assuming you were asking about temperatures, seeing that most folks use one form of 10w ATF or another.
If you're asking about synthenics in converters, I have no experience.
Some else will have to field that one.