My original hot water heater comes with 2 shut off cocks (p/n 7524043) The location of the switch is to the right of the steering column and states to use the existing holes below the column. The divertor control knob mounts to the right of the switch(further right). There is a 15amp breaker (p/n 8376915) which connects to circuit #11(hot) as Charles suggests. The breaker mounts to the back of the instrument cluster and there is a drop down resistor 5ohm wired across the switch for 2 speeds.
Yes. Blower motors are nearly always grounded through the mounting hardware. If it isn't, you will have 2 wires...a red "hot" wire and a black "ground" wire.