As I said, I really can't say about other Nations, but I do believe that language is more of a determining factor than geographic location.I guess part of what I'm wondering is exactly that: does your reading ever lead you to any indication of how the groupings are viewed. Will HaShem decide on the groups later, are they predefined, etc. When I think of "Nations" I realize that the entire EU can fall under one, but does it also follow that the migration to the US and Australia comprise the same? Or did they fall away from their original group, and form another group? I guess there isn't really any answer.
For Jews, there is a teaching that Moshiach will have the prophetic gift to tell what tribe each person is from. That will of course be of tremendous use when determining which Kohenim are capable of offering sacrifices in any new Temple.
Judaism does not place emphasis on reward in an afterlife. That does not mean we don't believe in one, but it means that what we do in this life should not be with reward in mind. What comes to mind is the analogy of Charity. In the ideal Charity, neither the donor nor the recipient know anything about the other. Totally anonymous. That way, the donor is just giving for the sake of compassion, with no reward or boasting, and the recipient is spared the shame of feeling obligated to the donor. It's the same with Heavenly reward. Do the right thing, for the right reasons, and that will take care of itself.I was also wondering if you could mention what your personal beliefs about death and afterlife. If there's one thing that seems to hold importance across the board in religions (although not without exception) is death. A mention on your own but also other MJ views would be interesting.
My personal belief is that there are four stages to the afterlife, at least of the Jew, can't say if it's universal.
First, is what we call Sheol, which is literally the grave. The soul stays near the body, lamenting it. This is the time when one feels shame for the wrongs one has done, as the soul remembers all. Not pleasant, and worse for some than for others obviously. This period has a deadline, and it's one year after death, but rarely do we expect this stage to take that long. Jews do not lay the grave's headstone until after a year has passed, out of respect for this period.
Second stage is a waiting stage. Waiting for the Final Judgment, that is. The souls of the Martyrs, for example, are said to wait under the Divine Throne. If the souls are aware of time passing isn't clear, but time likely has no meaning to them.
The third stage is of course the Final Judgment. There is no hell, the judgment is whether a soul should be allowed to continue to exist or perish. Not eternal punishment in a lake of fire, but rather something far worse... extermination for all time.
The fourth stage is physical resurrection for those judged worthy, in a new universe.
JMHO