First thing is a randomly weird catalog system that indexes with version control across alternate universes or something. Semi-runic.
Yeah, sounds correct on antipodal etc. Need to think on getting it right, my mind is starting to go numb at this point.
As for Adam and Eve. Remember most of these documents come from a particular interpretation of history/myth and so should not be taken as absolute truth. Or, call them metaphors that simplistically describe very complex things.
But in this theory there was one, which became two which became four, and then more: Adam and Lilith, Sammael and Eve were the first four. Eve convinced Adam to eat from the tree of knowledge, and they were expelled from the garden of Eden and into the Prime Material Plane. They became the first mortal creatures, while Lilith and Sammael stayed in the Garden of Eden as immortals.
The theory, therefor being is that Adam and Eve chose life and death and “reincarnation” whereas Lilith and Sammael chose Immortality (but reality sets in and the Phoenix Cycle still has to kick in, at least for lesser mortals)
As indicated by Tizzy in book 2, the real story of those four people? Not clear to anyone. Other than Adam and Lilith were once together, even as Sammael and Eve. Now some would argue that it was Sammael who tricked Eve (and thus Adam) into choosing to become mortal and experience life and death. But at this point only Sammael knows for certain.
As to how we get to other genders…not quite ready to figure that one out. One myth at a time.