I think the easiest way would be to put everything except your main character into an array and then adjust the ._x values that way, I think that should work. The other option that I can think of would be to put everything into a seperate movie clip the size of the entire stage, then adjust that movie clip's _x.

Maybe someone else could come up with a better way to do that part, but for your 2nd question, easy. You want the movie clip to be on the stage but not visible right? Just use moveClip._visible = false.