If you only select rich media does this effect anything? sometimes im getting 50 cents for a click other times a penny.. very confusing on how this works
I donot think that different ad format will help you in earning more. Only the thing would be click rate will increase by having different ad format.
Rich media has lower CPC, but higher CTR. And about sizes - the recommended ad sizes by google are the best one. (Large rectangle, 728*90, etc)