We’ve had some work done recently, which means I’ll be getting the paintbrushes out. As part of this, i thought i might get round to sorting out some issues that have been hanging around for a while, but i am not sure what to do

These relate to two main groupings : painting walls and varnishing floors

In the workroom, we’ve a couple of places where removing fixtures has taken us back to bare plaster. The paint on the wall is quite thick and would probably peel off if i got a sharp edge under it. How do i prep this for painting? Do i need a mist coat on the plaster? It’s been there for 20 years as it was plastered before we moved in

Just outside the workroom the paint is bubbling off the plaster. Again, how do i prep this please?

In terms of the floor issues, it’s quite obvious where Mrs NBT usually stands when working in the workroom. The damage is not quite as bad in the hallway, but the varnish there is also thinning. Do i need to take the floor back to bare wood before revarnishing?  What’s the best varnish to use? And in a serious note, should i be varnishing in the current temperatures, or might it be better to wait for warmer weather?

Apologies for layout, I’m using a tablet and it’s not easy to get the previews

1: I like Danish oil for wood. It lasts well and doesn’t need stripping to patch in areas. I’m told they have it on the floors at Copenhagen airport and only redo once a year. That’s some impressive resistance to wear.
2: I think that no matter how long ago the bare plaster was applied it’ll need a mist coat.

Go into your local Brewers (or local equivalent where the pro decorators go, Berwers offer phone support too.) show them the peeling paint pic.
They’ll maybe (probably) recommend a good stabilising sealer. Zinsser BIN perhaps. This kind of good base coat is pretty vital.