I also had Paul come over last night to give me a second opinion on the tub issue. After taking turns jumping up and down in the tub (no, really) and not seeing any movement, I feel a little better. It appears while they did cut into the top of the floor joist, they only did so to accommodate the drain so the rest of the joist is intact. I guess we won't have a bathtub falling through the kitchen ceiling after all. Which is nice.
You can see what's left for me to tackle tomorrow. I'm hoping to get the tub surround and ceiling tile taken down as well as the tile wall that goes behind the vanity.