My friend CL, your text reminded me how Bekenstein's theorem is called: "A black hole hasn't hair"! The theorem says that you wrote: When a black hole is formed, an outer observer can define three propertiesof the hole, mass, charge and spin.
We usually expect the charge to be zero because every black hole with non zero charge will soon attract and absorb an equal number of opposite electrical charges. So the only physical quantities that finally characterize a black hole is mass and spin. All the other details (the "hair" of the theory) lost at the stage of collapse. During the collapse we lose so many information and as quantity of information is related with the negative entropy of the system, we think that at first it's possible to define the entropy of a black hole. Due to the ideas of static physics, Bekenstein suggested that the entropy of a black hole is propotionable to the logarithm of quantum small-situations that has something to do with the whole mass and whole spin of the black hole. Anyway…
At the end it is said that what you wrote CL… the entropy and the area of the black hole is related.