looking great so far Ganna, as Dedman said the earth wire goes through the hole under the bridge, to the bridge pup cavity to the control cavity.
Just carefully file (not a rough rasp) the pickguard edges till it fits over the neck heel. Clean up the edges with some sandpaper when it fits. Also remove the pickguard and make sure the neck heel fits snug in the neck pocket, that may need a little sanding/re-shaping as well