No, there is no rule of thumb for this sort of thing. Properly stocking a marine tank usually means relying on someone with experience and who knows the animals, environment, etc. to help you. O2 regulation and usage in a marine tank differs from that of freshwater. Mineral usage by the animals differs in saltwater. Aggression levels, territorial habits, and overall compatibility differs greatly in saltwater. Filtration differs in saltwater.
A yellow tang that still fits into a 30 gallon tank with other fish at a yr or more old is an indication of a problem.
The best I can offer you is that all of the fish you listed for a 30 gallon tank would leave that tank overstocked, which explains the algae problems you mentioned. Average stocking of a 30 gallon is 3 - 4 small fish that stay small or 1 - 2 medium size fish that stay under 6 inches. 55 gallons can increase that to 5 - 6 small fish (small such as shrimp gobies... no larger than 2 - 3 inches each) or 2 - 3 medium size fish (up to 6 inches each).
These are maximum stocking limits for a healthy environment. You cannot compensate with extra filtration like you can in freshwater. Marine fish do not tolerate crowding... it greatly affects their overall health, growth rate, aggression levels, etc.
FYI, a yellow tang is considered a large fish and should have at least 75 or more gallons once it is beyond 3 - 4 inches. Yellow tangs are algae grazers, they will eat many species of hair algae and should have algae in their diets, such as algae sheets. If a tank containing a yellow tang has a severe algae problem, that is an indication that something is wrong. If the problem is slime algae that is an indication of over stocking/excess waste in the tank.
Live rock is extremely important in a marine tank. Live rock is not just decor, used for territory and etc. but it is also the primary source of filtration. At least 1 lb per gallon of tank size is suggested, but the more the better. There is no such thing as too much live rock in a marine tank, and the more is in there the healthier the tank and its inhabitants will be.
I hope this helps.