Can't say they ever need to be rebuilt, unless they're puking fluid, or pad life is poor (pistons don't retract). I've two Connies in the basement, combined mileage is over 250k miles. Never rebuilt a slave or master cylinder.
I'm partial to Galfer "green" pads for the front, P/N FD090G1651 (or 1651). Pad life is fair, and they take a bit to dry out when drenched, but they haul the bike down. Err, and I installed run-of-the-mill standard EBC rotors on my daily driver 5-6 years ago. They look spiffy, and don't seem to wear as much as the OEM rotors did. I can't compare stoppage to OEM's though, as it's been years.
600 grit is a bit fine IMHO. I use 220 (or what ever I happen to grab off the shelf) Wet-or-Dry if I ever need to buff the glaze off. Any visible scratches don't stay there long.
Not much, hope it helps,
Rick