Yes, but the effects depend on the texture. Light orange peel textures might let you put up wallpaper directly on a surface, but rough or highly textured surfaces (like knockdown or stucco) can make the wallpaper not stick well and leave an uneven finish. To get the best results, smooth the surface with a skim coat of joint compound, then sand and prime it before putting up the wallpaper. This makes a flat, long-lasting base that can be used over and over again.
Not if it's put in and taken out the right way. Modern wallpapers, especially peel-and-stick ones, are made to be easy to take off without damaging the wall. But if wallpaper is put up on drywall that hasn't been prepped or with heavy-duty paste, it can peel off paint or drywall paper when it's time to take it down. Putting on a primer or sizing agent first protects the wall and makes it easy to take off later.
First, get rid of any glue that is still on the wall with warm water and a sponge or a cleaner made for wallpaper glue. Wait until the whole wall is dry. Then, check for damage like holes or pieces of paper that have come off. Use joint cement to fill in the holes and smooth out the surface. Sand it after it's dry. Last, before you paint or put up new wallpaper, clean the wall and put a base on it.
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