I'm pretty sure that's all you need to check for on a regular basis. Just keep your calcium level between 400-450 (which I'm sure you already know).
As for trace elements, most people on this board would probably say just to keep up with your water changes to keep trace elements up and don't dose anything you don't test for. Depending on how big your bio load is, supplements like that get used up at different rates, and you don't want to overdose.
HTH