You don't want to add too many fish, because your bioload will be tough to keep up with. I would say 4 at most would probably work pretty well. I would stay away from Tangs. My experience with them in my tank has been that they become bullies, because the are cramped for space. You might try some Clownfish or some Gobies. Smaller fish would be the best bet. As far as corals are concerned, it really depends on the lighting. It depends on what kind you put in there as to how many. LPS, for example, will sting other corals. You also want to pay attention to the flow requirements of the different corals. I have my large
Bubble Coral in a lower flow area with my Flower Ricordeas, and most of my other corals are in higher flow areas.
Hope this helps some. I'm no expert, by any means!