Erick the plumber showed up at 9:45 yesterday morning, clean, friendly and quiet. I showed him around the house and pointed out the two problem areas - the broken hot water valve I broke off trying to close and the dripping ceiling. Fortunately the ceiling had stopped dripping by this time.
He opted to repair the basement valve first, which took about an hour. In the process, I did learn something I hadn't known. The valve that failed was a stem valve that looks like this.
Most of the valves in the basement are of this type, although a few of the newer ones are a ball valve with a lever. Some of the valves in the house are installed sideways, like in the picture, while others are installed with the handle facing down. Erick made the observation that the lifespan of the valves installed upside down is significantly less than those installed sideways or upright because small drips of water leak on the stem, rusting it. Which is exactly what happened to the one that broke off in my hand. Erick installed a new ball valve on the hot water and that should last my lifetime.
Then Erick headed up to the kitchen, climbed his ladder and started measuring where to cut. I left the kitchen. I did not want to be there when the lathe and plaster came tumbling down. I knew just how filthy the job was going to be based on the ceiling I took out in the basement and also on how dirty the water was that came leaking from the ceiling.
I asked Erick how long it was going to take to fix the problem, to which he replied that often what takes the longest is finding the leak. Here's a picture of the pipe he pulled out. See if you can find the leak.
The next step is to get the plaster guys in. We'll let the the ceiling air out for a few weeks though before we look at getting that done. It's still a bit wet up there.
So all in all, functionally everything is working great. It's the cosmetic part next that I'm most worried about.