File > Document Setup > Paper
You can change size of paper for all file.
http://www.youtube.com/watch?v=gqB-ER9Qdv8&feature=share&list=PL190C90DCE62242C9
One other little tip to get just the edges, view/face style/wireframe, this way you can select all the edges and paint them in one go and not have to worry about the faces.