Goniopora tend to do well with food. Then obviously any non-photosynthetic coral. Some gorgonia are in that category, be sure yours is not.
Feeding definitely optional, it does help the corals grow faster a little bit. Though you shouldn't be worried about it spiking ammonia and nitirite, only nitrates really. Obviously that is the byproduct of the other two, but if you ever have measurable levels of the first two you have bigger issues.
I am currently in the process of restarting some of my culture tanks. My plan is to produce phytoplankton to feed copepod cultures, rotifer cultures, and feed the tank with it. The pods are for a mandarin, the rotifer will be to feed corals.