There's more than one way to apply the popcorn. I removed it all from the ceiling on my first floor. It was relatively easy. The stuff became soft when sprayed with plain water, and then it just scraped off like it was putty. If it has been painted over, that certainly won't work!
If there are any plasterers in the area, some of them are true artists, and can make a funky ceiling look glass flat and smooth.
No idea what a stretch ceiling is...can you elaborate?