Geoffrey Rush as Stoic? I could see that, though that character has quite an accent, he would have to tone it down slightly or else you run the risk of turning Stoic into a complete cartoon.
As for Morias, he's actually quite young in elf years, so I figured he would have a voice that sounded like a teenager.
Cade's tricky. On the one hand, Edward Norton's voice would be great for the moments where he gets into those anti-Equipment King rants, but he also might come off as a bit too old. I can't really think of any other actors off the top of my head right now, though. Any other ideas?