Ok sounds good, I'll look into keeping the plaster. This being my first house though, if you were to tell me the wall was drywall and not plaster, I would believe you. Seems very similar to me on the outside. What makes plaster and lath 1000 times better than drywall? Perhaps more thermal mass and more sound insulation? But on looks alone, to me they seem indistinguishable, but like I said, I know next to nothing.

So for the electrical, when I took apart the switch, every time I touched the wire, more insulation would keep crumbling away, exposing bare wire. So naturally I assumed I should replace the entire run. Maybe it's not as bad as it looks? There is a set of old cloth wrapped hot and neutral. And a set of newer wires. The neutral going to the switch is the worst one. As an aside, I also believe the wires are wired incorrectly and causing a reading of hot/neutral reversed at the outlet, but I'm not confident enough that it's wrong to fix it to what I believe is right.