when removing the popcorn spray the ceiling,mist it with water.we used a pump up sprayer wet a small area let set for a little bit then scraped it off.it's easier to clean when wet. Besure and use a good respirator don't soak it just lightly dampen makes thing work better.also cover anything you don't want it on.
+1. I've removed asbestos tile and we would spray it with water to keep the dust down. Getting pro's to do it will cost a bunch I bet.