[84porsche]

I would think if you wet it /soak it really well it should break up the popcorn or soak with a paint thinner first and then soak with water to break up the popcorn part and scrape. I haven't done our house yet but it is on the list. To put drywall over the existing you are going to make your room(s) much smaller by at least an inch depending on thickness of the drywall. I just demolished a bathroom, now putting it back together is the problem.