Hi! I'm in the middle of renovating our 1920s bathroom, and would love some advice about repairing plaster walls. I've pried the old, ugly ceramic tile off the wall, which has resulted in quite a mess. Behind it are various sections of plaster, wood, and painted keene's cement. See the attached picture. The cement was scored to look like tile. There's also a square panel of wood, as well as a horizontal wood piece that runs the length of the wall, about halfway up from the floor, which divides the wall into two sections. I don't think it's possible to remove this piece, as it seems to go back deep into the wall. I am considering one of two options:

- Installing a thin layer of sheetrock over everything. This will increase the thickness of the walls, which I don't care for, but it does seem like the simplest option.

- Apply a skim coat of plaster (easysand?). This seems like it would be the best option aesthetically, but I am wondering if it will properly adhere to all of the surfaces I have exposed (plaster, wood, and painted cement)? Would I need to prep any of these surfaces before proceeding? Also, there is some variation in the depth of these surfaces, maybe up to an 1/8 of an inch, so I don't know if easysand could smooth that over.

Are there any other options I should consider? This is my first project working with plaster, so I'm definitely a beginner. Any advice is appreciated :)

Thanks!
Dave