Evilhalfling
Adventurer
also check out athas.org
This. it is a fan supported huge collection of info.
I assume you started with the Darksun 4e book? crucial so you don't have to reinvent the wheel -
defiling is one of the defining things about the setting, but the mechanics were always a little wonky.
Old adventures:
Don't play Freedom - the NPC heroes do all the work, leaving the PCs as spectators. I think Road to Urik was better, PCs got to assemble and army and it had good encounters as the army journeyed to attack/fight another city.
I liked the first of the novels - but the rest sucked. They did some neat things with the flavor/visualization of psionics, but 4e psionics left me bored. 3.5 was the best version of Psi.