Yesterday I felt that I got to a good stopping point on the ceiling, so today I decided to take a swing (literally) at the walls. I started on the wall that divides the space in two (the one painted orangey-hot pink). It was very slow work, and harder than I expected.
This dividing wall was built between two other walls, which are not aligned with the brick wall of the house in the same way (the basement's back room has drywall right up against the brick; the front room's walls are 8-10" out from the brick. Weird.) Here you can kind of see the gap.
I was mostly using my hands, feet, and occasional hammer blows to push, pull, and kick the drywall apart.
After three hours of work, I accomplished....not much. But it's a start!