I think that's great the the teacher is willing to differentiate. Flexibility and a willing teacher is really a big part of having a good year. I like your son's suggestion of doing roman numerals - maybe she can take him up on his offer and have him do his math in roman numerals while the rest of the class is doing 1 to 5, for starters.
I'm not sure about OT stuff, but I would say it probably depends on the situation whether or not it's useful to share the IQ/GT information before the evaluation. Even if the OT doesn't find that your DS doesn't qualify for services, I am sure that they would be full of useful tips that you could use, and I think the tips could be better tailored if you gave the full information. Hopefully someone with experience in this area will chime in.
