Actually, I believe performers are artists, generally speaking. Like anything creative it's a question of accomplishment, and of significance. Creating can be in the execution as well as the concept as far as I'm concerned. e.g., Louis Armstrong is primarily known as a performer (didn't write all that much), and yet he almost single-handedly created modern jazz in the mid-twenties. Or so the story goes. And while we're talking about Louis, I would place him in category (c) rather than (a), seminal early output, followed by less and less relevant stuff, slow-ish fade to black (pardon the quasi-racist pun) and almost a caricature of himself by the 1960's/70's.

Nobody's actually answered (or attempted to) my questions by the way.