Yes that’s a precursor to modern Sheetrock. It came in 2’ wide strips that then had a 1/2” layer of plaster applied. Heavy as all get out. If you are doing renovation do it correctly and remove this surface in the kitchen so you can upgrade all the electrical , plumbing, and insulation. No need to add strapping to the walls and no this doesn’t hold up the roof.

Absolutely it should all come down. Its called gutting a room, so that you can inspect all the old wiring, and do proper insulating, etc. The ceiling should probably be taken down too. Best to put up all brand new.

If that is galvanized water pipe I see in the wall rip it out and replace it.

@outpaientzero, it is galvanized pipe left in the cavity. Not sure if it was originally supplying the sink or spray, it is not used. Will find out more once the wall surface is out. Home was re-piped with copper 16 years ago.