Hopefully, you will not have to do a lot of heavy sanding of drywall compound...if it's applied correctly, you can whack down the high spots using your mud knife as a scraper after a coat dries, apply the next coat, repeat. After three...there should be little sanding to do and usually it can be done with a small amount of sandpaper in your hand. If you do choose to power sand, take care as the paper is thin and consider using a wet collection bucket in-line with the vac to capture most of the (abrasive) compound dust. You can get that at most of the 'borg stores. Personally, I wouldn't use a Festool sander for this purpose...just a choice of my own.