Some of what you seek is available here on Sailboatdata: https://sailboatdata.com/sailboat/vega-27-albin/. “Deadweight” would be the displacement. You could also use the plan drawing (it is to scale) to determine what the freeboard is. You will have to define the “total height of the side”. It is not a common term. When these boats were first built there may not have been an official “number of people on board” maximum. Now, the number might vary according to requirements in different countries, or might vary depending upon how the boat is being used. Six people might be needed for overnight racing, for example, while in a day race having that many on board would be very crowded.