Now that I have reached Brimloch Roon, what should I tackle next? I have gone to all the guilds in town and picked up all the quests. I actually already took care of that centaur who stole the helmet from the guy at the armory, but that's all I've done. Most of the quests I've gotten have to do with the Temple of Isis or Skull Castle; does it matter which one I do first? Thanks!

You have to do Skull Castle before the Temple of Isis/Anephas' Tomb.

Other than that, explore explore (and collect crab shells)

Wyv