I would think if you used a steamer to get the paper off,they make other products that will aide in removale too.
Then sand to get a nice etch in it,next put a nice skim coat (drywall mudd) on.
I would assume this would cover any minor improfections.Sand and look for pinholes or other improfections if needed put a 2nd coat on.Then prime,and paint.
There may be many ways of doing a project like this.
Good Luck

I agree that a steamer will be the best way to get the old wallpaper off the walls. It depends on how bad the walls get torn up but you may have to seal them with GARDZ from zinssr before you skim them to keep the face paper from bubbling up. I have seem this product used it works great.
You may want to think about going with a satin/eggshell rather than a semi-gloss as the more shine the paint has the more the rough spots show up.

I totally agree eggshell sheen semi-gloss will show the bad spots.