There is no regulation stopping you from solo-ing in a Twin engine airplane.
Highly unlikely as no insurance company would allow this so unless it is your own airplane it's not gonna happen.
Probably the owner let him fly the airplane under supervision.
Maybe his mother does not know which airplane he flew for training.
My mother for sure did not know what type I was flying.
Anyway, concur with
chances of his own and his friends' survival were almost zero