Interesting. Trains are all diesel electric and the only purpose of the diesel engine is to produce electricity that drives the train and charge a battery system to start the diesel. Little more complicated but this is basic.
Yes. I've wondered about this before. Some ships work this way too. Seems like a diesel/electric combo could be very interesting in vehicles. The diesel (or a turbine or whatever...) is always operating at it's most efficient RPM, and the variable demand for torque is handled by the electric motor(s). Sounds like an interesting thing to me.