We are considering replacing our plaster with drywall (house is 60+ years old). We are trying to determine if it is worth or it or just to try to repair the plaster. Some rooms have heavily damaged walls from a leaky roof and possibly poor workmanship. Can badly damaged/sagging walls be fixed or do they have to be torn out?

Do repaired plaster walls look good enough to paint, particularly after stripping wallpaper off them? or is it best to re-wallpaper them?

Is it true that you have to compensate for the thickness of plaster walls and shim out the dry wall so that it lines up with where the plaster wall was previously? (in part to accomodate the wood flooring which is installed for the plaster wall thickness).

What tools are needed/useful to tear out plaster?