(Note: This is the first of the unanswered questions about ITC, the afterlife, and our ancient heritage that I hope to find answers to in this series of articles.)
Question 1: Assuming the Edenites were busy terraforming all (or most) of the inner planets of the solar system, how did physical life on Earth survive after the explosion of Eden/Marduk, while all the other planets became barren during the holocaust?
Best guess: Earth might simply have been on the opposite side of the sun when Eden exploded.
This picture shows the approximate orbit sizes of the inner planets, including Eden.
The picture below, showing the relative sizes of the sun and planets, suggests how our world might have been protected from the blast. If the massive sun stood directly between Earth and the exploding Eden, it would have been like standing behind a brick wall when a grenade goes off. There’d be blast concussion, but maybe no other serious injury.

(picture courtesy of NASA and Martin Kornmesser, with my addition of Eden)
So, that’s the scenario the makes the most sense to me:
Survival of life on Earth 4 billion years ago was just a matter of being in the right place at the right time when Eden (Marduk) exploded.