Is the magnetic firm reusable? Can it be pulled from the wall without hurting the drywall? Does the film come in white.

This film is white in color. It is repositionable during install, but sets up after that. More than likely it will bring some primer/paint with it when removed down the road. There are many things that can affect how well it does or doesn't stick to the wall though, so every install will not be the same.