The Encyclopedia Astronautia website is a terrific resource. I've used it for years. You can spend many, many hours there and still find surprises.

As for the different flying platform proposals, I imagine the proposed vehicles would've been very maneuverable. With the low lunar gravity, there might've been a concern about stability. It might've been too easy to overcontrol.

There would've been a real problem with kicking up dust, especially during takeoffs and landings. Not only would that possibly be blinding, it might cause problems for experiments. That, combined with the greater speed and altitude could lead to a greater chance of an accident. While they could've done some training on the Earth, they might've had to basically do some hasty adjustments in the lunar environment. Look at the trouble they had walking on the moon. Imagine having to learn to fly there.

They might've also been concerned about the difficulty of judging distance and altitude while flying over the lunar surface. In the end, if one of the motors on the Lunar Rover failed, you still had 3 other ones (one in each wheel) to get you home. If the rocket engine failed on one of those flying platforms, you're going to go splat.