I use power sanding for almost all of my bowl work. Done correctly it will reduce the radial sanding marks that are characteristic of hand sanding. The key to any sanding is "light". Light touch and light angle. By applying a light touch and preventing the sanding disc from digging into the wood, you should be able to progressively remove the sanding marks from the preceding grit. By light angle, I actually mean visible light cast on the work surface. I will frequently remove the work from the lathe and pass the bowl under a bright light or sunlight to look for sanding marks. This will drive you crazy when you keep seeing those telltale swirls from lower grits, but it is a necessary evil if you want a pristine surface finish.
As for direction or rotation, the sanding disc should be rotating in the opposite direction of the work item. Thus if the bowl is turning toward you the sander should turn away. If you reverse your lathe direction... and you should if your lathe allows it, then reverse your sander.
Speed is more of a judgment call for me. I try to keep the lathe running at less that 200 rpm and the drill is usually at 3/4 power... again a judgment call. What I try to see is, how well the surface removal is going, how much heat I am generating, and how clean the surface is looking (swirls). Did I mention that heat is your enemy? :wink_smil
Anyway... I am not a sanding expert by any means, so all of the above is disposable information. It is just the way I do it and will likely be eclipsed by better advice as the thread goes on. Best teacher in my opinion, is experience, sand 'til you feel comfortable with your technique and your results.
Happy turning... and sanding! :icon_thum
