Alright, here to clarify some things.
1.) No skimmer is required, it is unnecessary and expensive. Water changes will support your nutrient export completely
2.) The amount of rock you have is perfectly fine. Just because you plan on having a reef doesn't mean you need more. Actually, often time FOWLR
fish have bigger bioloads then reef safe ones.
3.) In order to support any photosynthetic creature your lighting needs to be upgraded. Tao panels are the best for the buck. One will do you good.
4.) I don't keep my rocks on the glass whether the back is painted or not. I feel safer with the scape knowing it doesn't have to rely on another structure to be
5.) You can have more fish then 2 clowns. The most common amount is 3., but if your system is really that reliable after some time (6-12 months) a fourth fish is possible.