Caliper brackets and pads the same. Actual caliper is different.
94-98 use 38mm pistons, while 99-04 use 40.5mm pistons.
Yes, with an asterisk.
There are two banjo bolts, coarse and fine. I beleive 94-98 are fine, and 99-04 are coarse. But i could be wrong.
The are interchangabe, however the 99-04 calipers would be more suitable for a 99-04 GT because the master cylinder on the GT and Cobra those years is the same size (1 1/16"). The smaller 94-98 might give a slightly firmer pedal, but more than likely it won't be noticable due to the tremendous amount of assist hydroboost gives
True they may only be 80 dollars but make sure there ain't a core charge on top of the 80 dollars