You will ber quite limited in the fish stocking area, but you can add quite a few corals if you have the filtration and lighting for them. Shrimp and crabs do not count towards the bioload.
A reef tank has 1˝ - 2 pounds of LR
per gallon of capacity, or 30-40 pounds in your situation.
How long has this tank been set up?
Are you cycling the tank with the damsel?
If so, please attempt to bring it back to the store till you have cycled the tank using the fishless method (see the articles section on this forum).