Yes by better pad I mean the K750's over the K500's.
If you're doing track days, then I would strongly recommend the K750's. The K500's aren't designed for track.
Yes, there is a trade off in rotor wear from the K500's to the K750's, however I think its negligable.
You'll probably find your brake fluid will boil well before the pads reach their max temp. If you're going track, get some Lucas brake fluid.
Cheers