I did a full cut and buff on my DD a while back and used 3"/6" 3M Trizact discs paired with my PC 7424XP and it worked absolutely beautifully. I would suggest doing your final pass (3000 or 5000 grit) with a small throw finishing DA though. I used my pneumatic DeWalt palm sander for this. IMO if you're going to be paying for a sander and already have an air-DA, you should just get a PC. Capable, well-built tool and can be used for polishing to perfection as well, which the linked tool cannot.
I would not recommend using a rotary for any type of cutting, unless you're intending to strip to bare metal for a respray. Lol. The action of the DA is much more gentle than a rotary. If this is your first time sanding clear coat, I would highly recommend that you research THOROUGHLY how to wet sand by hand/by machine and make sure that you understand just how thin the clear coat on a factory paint job is. Wet sanding should not be taken lightly, as if you break through to the base coat, the only repair method is a full repaint of the panel. There are many great resources on AGO about this topic. Just do a search for wet sanding or machine sanding clear coats.
