1. Why does 120V need a neutral wire, but 240V doesn't?
2. Other than two wires sharing the amperage in wiring a 240V motor vs wiring it for 110V is there an advantage for starting the electric motor since the two legs of the 240V wiring are 180 degrees out of phase with one another?
In essence any electrical device is operating as a controlled dead short. Two legs are hitting each other, either as a 120 volt circuit, the power leg is hitting a neutral, which is a grounded wire, or two power legs in a 240 volt circuit are hitting against each other.
No. Usually a device is 240 volts to eliminate having to upsize wiring and breakers. Thanks J