Looks like it. They got a tow to somewhere with reception but the car wouldn't start. That implies they did get into it, but were still stuck due to the dead battery. So presumably the door unlock system has it's own backup battery?
No, the power required to unlock the door (a small motor) is usually a lot less than the power required to ignite the fuel. You'll probably find that the radio and internal lights still worked too (though likely not for long).
To turn the engine. Lighting the fuel is easy enough. But overcoming the pressure inside the engine and getting ~50lbs of metal reciprocating and spinning from 0 to 1500rpm in a few seconds takes a bit of a kick.
