Ok, I took out my multimeter and went down and took the cover plate off the GFI outlet. Like I said, coming in I have black, white and copper. Going out, I have the same. Black in goes to line on outlet, black out to load. White in to other since of line on outlet, white out to other side of load.
I put the multimeter on the line black and the line white and read 120v, then put it on the line black and ground, read 120v, then put it on the line white and ground and got 0.
Did the same test on the load, same results.
So I think that verifies my white is neutral (it also goes back to the neutral bus on the panel along with the copper) and I can wire like this:
1.) Above GFI (away from panel), black (hot load) from GFI to line side of XPS3
2.) white from outlet box to one spot on neutral side on XPS3
3.) Out of load spot on XPS3 to rest of circuit via black
4.) Out of other spot on neutral on XPS3 to rest of circuit via white
5.) Copper in to switch box from each side pigtailed around ground screw in new switch box
So on the XPS3, line has one wire, load has one wire, control has no wires and neutral has 2 wires.
Does that sound right?
thanks!