Just so you know what to expect.....
I was also told (a few years ago..!) that it was not a plane, but an AEROplane. It now annoys me when people say plane, and I now say aeroplane all the time.
Will go for answer to number 2, and that's that it's aeorPLANE as the plane is the wing, which is the magic bit of it all.
tKF