WRT question 5, it is because pilots who grew up on Cessnas and Pipers, got their first professional experience in King Airs, don't trust AC power, just as they don't trust hydraulic flight controls. I am NOT being flip, I have lots of personal encounters to justify that statement. I have been told Challengers and Globals are DC airplanes with all the AC power converted to DC thru the TRs.
GF