Copper foil isolates the pickups from outside radio signals
About the second question -- help with what?
Not sure about the diagram, is there a single volume and a single tone knob or two volume knobs?
edit: nevermind, it says it's a single volume and single tone configuration in the description. I'd say it's not that difficult to work out what goes where based on a different guitar's diagram, but I'd have to catch up on the correct polarities and serial or parallel connections, stuff like that