Really… you should consider re-plastering all surfaces with perhaps Plaster Of Paris or even Joint Compound… then finish off with Spackle where necessary locally, then prime with Pigmented Shellac Sealer Primer, then finish with a High Quality Semi like Sherwin Williams Classic-99… advise installing an exhaust fan or always crack open the door when taking a shower… use a fan to ventilate while doing all the painting work…

I feel your pain that is a messy job. You will need to skim coat your walls or you could do a knock down on them depends on the look you want. You should lightly wipe your walls down with water to get any left over glue off that the wallpaper may have left behind. Let them dry for a day or two then sand them before priming them. Using a shellac sealer primer would work best for this, making sure to have ventilation when using this as well with all paints. Then sand again before doing your skim coat or knock down, this will help out with the finishing. Let them dry good, sand again (I know there is a lot of sanding to do). Do any touch up on the mud work sand that.

I like to prime my walls again using a Hi Hide Latex Primer that is tinted at least 70% of the color that am going to be using for my finish coat.(Helps with covering and works good when using dark colors). I tint all my primers dark or light colors sealing the mud work making sure not to have any dust from the sanding before doing the top coat. Lightly sand again.(A pole sander works great for this kind of job and makes all this sanding faster). Then you will be ready to apply your finish coat or coats depending on the color your using. A quality paint like Sherwin Williams Duration Matte or Satin finish, Cashmere is a good one to use if wanting a good washable paint. These are high end paints Promar 200 or Super Paint interior are a medium paints. I hope this helps you out good painting to you.