2. My short answer would be "no -- I personally believe it is the same information / knowledge / gnosis." I usually refer to this body of knowledge as simply the "ancient wisdom."
so, what is part of the star myth download/teaching is unique/special/different?
1. This is a difficult question because what we have is a pile of evidence that the myths from around the world encode the movements of the stars and heavenly cycles, as well as compelling evidence to conclude that they all appear to be using the same system...
moreover, I think looking at star myths as one aspect in a grand, multifaceted, interwoven body of ancient wisdom strengthens your hypothesis.