I would avoid the 87s but only because if the CDI dies, they are harder to find. 88-2000 have drum front brakes. 01-current are disc fronts and a carb change, other then that there are few minor changes.
This thread has some info about tuning the front forks. As a note Mr. Brackets website is having custom springs made to fit TW forks for more tuning options.
I can't answer the other questions, but I am sure someone who can will be by shortly.