The wires for the Neutral switch run behind the left side panel, down the frame tube and then under the gearbox, the switch is earthed using the brown wire that bolts to the gearbox bolt near the gear change. it's always wirth pulling the connector under the side panel apart a few times to make sure the connection is made but I suspect your neutral switch is scrap.
The rear brake light switch is behind the passenger foot peg mounting plate on the right side of the bike. If you peer down from the top you should see the rubber cap for the switch. There's an adjustable locknut that needs tweaking to get the switch to work correctly - the fact that it's on is a good sign.