1) As I understood it, the origianl calculation about bees not being able to fly was considering them as a fixed-wing machine and looking at the body in an air tunnel, which correctly predicts that a bee without wings in motion has little or no lift. I never heard the part about the brain not being able to send the "beat" signal often enough.
2) The science fiction writers have beaten you to it-- Robert A. Heinlein in "Jerry Was a Man" (about 1948!) discusses the problems which a very rich man encountered when he wanted a flying horse as a polo pony. (And many other problems too-- the story is one of the best arguments against racial prejudice I have ever read, and I count myself lucky to have read it while I was still under ten and those attitudes flexible!)