In my area, building codes require the walls to be secured to the floor
with fasteners. I used Ramset nails and cracked the slab at one place.
It's tedious and not as fun as gunpowder charges, but masonry bolts
might be safer.

Don't attach drywall to block. It *will* mold. Would furring and
styrofoam board insulation fit?

Also remember that block walls are not straight or plumb.