After posting a similar question in the past, we have decided to stay at the Polynesian pool during the day of the 4th to avoid the huge crowds. We are then going to Epcot for dinner at Le Cellier at 5:00 pm. We will then stay for the Epcot fireworks show.
According to others who have been there on the 4th, Epcot handles the crowds much better than MK and the fireworks are supposed to be fantastic. I am sure AK and MGM would be less crowded than MK as well, although I don't know what type of shows they will have.
As for other festivities or activities during the week, I have not heard of any.
I think the 4th will be great!