Take a look at rockler for the leg adapters. These and these look promising.
Wire things in parallel as others have said. If any part of the frame is metal, such as the reflector then you want to ground that in case one of your wires comes loose and touches it. Without grounding it you won't know until you touch it. I would try to avoid any metal in the frame so I could not worry about grounding it. If your light sockets have ground screws use them.