First step completed: 2 shutoff valves/drains installed on the pipes that sometimes freeze in -40 cold snaps. These new shutoffs also make it possible to work on the sink/dishwasher without shutting off water to the whole house, which makes this whole project a LOT easier. Yay.
Tomorrow will be ripping out the old sink and cabinet and hoping that the floor underneath isn't rotted through into the cistern underneath...