Thanks for the replies

The boss soul trades sure are strangely distributed with some having one possible trade and some having several (and maybe some with none? I don't recall Straid's spell list off hand as I'm not a caster this playthrough). Makes me feel like there's another vendor out there somewhere beyond just the two known ones.
Couple more questions that popped into my head:
1.) What is up with the burning platforms in the Iron Keep, specifically the ones with items/chests on them? Naked or fully loaded up with as much fire resist gear as I have, I can't seem to get the goodies. I feel like I'm missing something really obvious here but I'm stumped. Only thing I can think of is it somehow relates to the Smelter Demon as I haven't killed it yet (not for lack of trying).
2.) NPC clothing, particularly Straid and Lucatille. Is there any way to get their gear? I know I could kill them and maybe get it that way but I'd rather not if it's not even going to get me the goods.