I can say for sure on the '03 ST4S-ABS that:
1) Yes
2) Yes
3) 4,000 miles and not a single malfuncton. Will take vacation on the bike two-up again this year - so I trust it.
4) I have yet to trigger ABS, even in the rain. The rear brake is not very strong and lacks feel which I think ABS contributes to.
Headlights are weak on '03 and before so you will not want to go out at night with the Ducati Designs headlight.
Stock seats are tough on '03 and older. If you get a Corbin and are less than 6'2" then I would not get the standard seat back - get the shorter rider seat length for support and give the space to the passenger. I would read up on break-in on this site.
The '03 and older fairing front ends look more Italian.
Incredible suspension and high speed steering and tracking.