You do not need to use the 5v for anything if you don't want to. It is not necessary for the operation of the keywiz.
As far as the ground connectors, you need to have a loop of ground wire going from one microswitch to the other. Use the daisy-chain method. You have to make sure that every single ground wire is connected to the terminals and then returned to the keywiz. You HAVE to have a functional ground connection.
I know this is an IPAC, but you should get the idea.
