Good question that I have not really seen a definative answer for. FWIW as I am pretty new to the buffing deal, I use the Stewmac arbor buffer (runs at 860 rpm) with the Menzerna fine and extra fine compounds. For me, I have found the best results (on nitro lacquer finishes) lightly loading the buff by holding the compound bar on the wheel for no more than 3 seconds with light pressure. Loading more than this usually causes the compound to buildup on the guitar surface which then has to be wiped off with a damp cotton cloth. I usually load the buff with a single compound no more than 3 or 4 times for a complete guitar. While buffing, I apply extremely light pressure to the guitar. At 860 rpm you really won't have any burn problems by applying light pressure and by keeping the workpiece constantly moving.
As for reaching into the cutouts, I get in as close as I can by angling the guitar without hitting the steel washers and arbor nuts, then finish up by hand. I learned the hard way not to try an get the guitar too close to the spinning metal parts
Also, I both the fine and extra fine compounds do very little to nothing to remove scratches. That being said, I have been wet sanding with micromesh cloth backed "sand paper" starting with 1800, 3200, 4000, 6000, and 8000. I am thinking of trying some additional buffs with coarser compound to see if I can eliminate some of the labor involved going through all the various grits of micromesh.
Good luck! - gpp