1) That’s a reasonable thing to assume can't say for certain thou I haven't seen them all.
2) Why do people kill in the name of a god of peace? People are really stupid. What does Corath promise, what does Pyrtechon promise? Power, and more power, people which don't have much foresight tend to flock to these gods. It helps make them beatable if not by their conviction alone. That and a promised afterlife is basking in the glory of whichever god it may be with slaves and mead, when in truth it’s him basking and you’re the slave.
3) In theory yes, but I doubt it happens often and when it does the soul mother is very annoyed. Even then I recal some post somewhere where even then the soul has to pass thru the plane of lost souls.
4) I doubt that, the planes are highly remote to the people of Layonara. Myth and legend, the deities may not even hold court in them and most would never know. However Ozy could probably tell you what HE thinks, not that he is necessarily right. This perception is because I don’t even think the planer material is all written yet which means my logic may not be Ed/Leanthar’s logic.
5)
http://www.planewalker.com/index.php is what Ed has sugested; there are a few published manuals. But both are built towards a greyhawk/forgoten realms setting. So that leaves a lot of 'tweak this or that' for the planes of Layonara. Best person to prod about it is Ozy since he spends most of his spare time in some hideous planer local. Even then anything he says will become rapidly outdated and inaccurate as the planes progress and I can’t get my hands on the information fast enough.