I have plaster in two rooms. I've taken off the wallpaper (well, more like helped it to peel off). In the kitchen the plaster is in terrible shape, lots of large rough patches using plaster, joint compound, some harder cement, etc. The living room is in better shape, but still has many patches. I've also replaced really damaged places with drywall.

There doesn't seem to be any kind of smooth finish coat on this plaster, it's quite rough.

How can I prepare these for painting that will give a consistent surface, ideally smooth? If I decide to use wallpaper in the kitchen, is there a specific kind that will be stiff that can hide some of the lumps and bumps a little bit? [The kitchen is scheduled for a total rennovation in several years though.]

* Skim coat everything with some material?
* Is there some kind of paper or canvas that can be applied first?
* Is there a thick primer that will hide the roughness and apply/dry smooth?

Thanks for any ideas!!