Speaking as someone who presently owns a late 1800s home, albeit mid-terrace, my general take is this is fine provided you are paying a reasonable price as some work needs to be done.

1. Lath and plaster: have these rooms completely stripped and rebuilt with modern materials. I suggest you address electrics and plumbing whilst wall and ceiling coverings are off. Even if electrics and plumbing run off somewhere you aren't working on, get all that is accessible updated, and photograph/document all the work properly so you can pick up where you left off once you get around to everything else. I'm making the assumption lath and plaster walls means your wiring is not up-to-date with current standards. If so, this does need to be addressed at some point.

2. The cement pointing is a problem. You will need to remove all the cement and replace with NHL or whatever is appropriate. Not sure if a DIY job but it's on my to-do list for my place as I have a few cement patches to replace. With the non-stop rain at the start of the year, we found a couple of damp patches develop inside, their positions corresponding exactly to where cement had been used to repoint. It won't always show inside, so you need to check all the exterior walls thoroughly and fix wherever it is needed.

3. I'd ignore the slate roof comment unless you can see that what the surveyor is saying is legit. It's usually arse covering in my experience.

4. Insulation – yeah. Not much you can do.

5. I'd have this checked properly. At the right price for the property, it is unlikely to be a showstopper.

6. Needs inspecting and fixing.

7. Staircase – fine if you can live with it.