Well, you must obviously use a screen mode with full 8bit colour depth (and if you’re extra adventurous, it’s even possible to hack HAM8 mode). Then you need the appropriate datae type for the backdrop images you intend to use as backdrops, and enough RAM (and patience) for them to show up.
Regarding closing all windows, if you mean all workbench windows, then yes, that should be possible through the arexx port of Workbench, so a script you can attach to a hotkey or menu entry could do that. One may argue that this is really something that should be a standard entry in the Window menu.
