Cook the pasta according to package directions. When cooked, drain and put in a large bowl; add remaining ingredients. Do not add the liquid from the olives or pepperoncini. Do add the liquid from the other jar ingredients. Mix together and refrigerate until ready to serve. You don't need salad dressing because the liquid from the marinated vegetables is enough to coat the pasta. When serving, place the halved tomatoes on the base of an open bowl and mound the pasta salad on top.