Coming from a commercial demolition guy …. good luck! If it were me demoing that house, I would cherry pick all the sheathing from the exterior and call in the big guns to finish it off. Busting up all that plaster and hauling it out is going to be a lotta work. If you can work the structure from the outside peeling away the siding you should find a lot more of that nice wide board lumber.
Fwiw - those boards will exhibit a lot of staining from the lath. It must be a different species thing that causes the staining.
Ill be following and rooting you on Pete.
Say it with me …. "NOW THATS HOW YA DEMO!"