RE: "Are these arrangements original, and do you perform your own background parts?"
Yes, everything is original -- and spontaneous. In other words, nothing is rehearsed (and rarely played twice, at least not in the same way). This is the whole idea behind the website and videos: to teach others to be creative and spontaneous. By definition, "improvisation" means to create something unique -- on the fly. And yes, I do all the background parts with the exception of the drums. Thanks for asking.