Just a simple question related to this. Assuming I want to remove all the
drywall along a wall - if I wanted to keep the ceiling intact, should I run
a knife along the corner first to break the joint tape?

I guess I'm wondering if pulling down the wall will shred the ceiling
regardless of how careful I am doing it. I guess in some regard I have to
feather the corner when I retape so maybe this is a moot point anyway. or
maybe I can cut the drywall say 6 inches from the corner and not remove the
wall all the way to the ceiling then that makes installing the repair a bit
simpler.