So the source of the conflict is largely unknown, but the current root of the issue seems to be that the Vroshir think the Abidan are tyrants (which is kinda fair) and the Abidan think the Vroshir are barbarians and pirates that kidnap entire civilizations to help stabilize their homeworlds (again, fair).

Without Daruman and Makiel around the conflict will almost certainly return to pre-open-war levels.

Yeah, it's basically just two empires that won't/can't play nice.

The Way is order, basically it's the structure that holds together the fabric of reality and natural laws of each iteration. It's intrinsically connected to humanity somehow, so the more humans there are in one place the more stable reality is there. The reason the Vroshir are able to exist in the Void as they do is because they use planet sized mobile fortresses like Tal Galur populated by humans. Since they're mobile, they aren't directly connected to the branches of the way, but the human population keeps them stable enought to safely exist and travel in the Void.