I have used copper for rust. Works really well and lasts a long time. You can typically see a blueish hue on the leaves as long as it's there. I haven't needed to use it more than once or twice in the mid and late summer to have no rust problems at all anymore.
I have used sulfur for mites, but its also quite effective for rust/fungus in my experience. I have only actively fought mites once and alternated sulfur and spinosad, maybe twice each, 7-10 days apart. That seemed to solve my problem. Now I mainly use sulfur as a dormant spray with some horticultural (mineral) oil since I have that 'lifetime supply's bag from bonide. I also had some pear leaf mites last year and sulfur has really seemed to help with them as well.