1) What yarn (that you don’t have/haven’t used) would make your stash “complete”?
Ummm... tough question. If I had to pick one right this second, I would say Rowan Calmer. I have heard so many wonderful things about this yarn but I've never tried it. And who doesn't want something named calmer?
2) What yarn do you never want to be without?
Besides yarn in general? :-) I always want to have something in my stash that inspires me to pick up my needles.