Belbab, I can provide some vague information about WT burials.
In the days of CTR burials of Bethel family members were at the Pittsburgh cemetery with the "Russell pyramid"
After the Society left Pennsylvania they acquired some farmland on Staten Island in New York. At that time Staten Island was like another planet in terms of accessibility: there were some bridges from the New Jersey side of the island, or the Staten Island ferry from the southern tip of Manhattan. In addition to growing much of the food for the Bethel family, the Staten Island property provided a hideaway for Rutherford and his personal secretaries. Eventually folks realized that even Staten Island was too close to Bethel and that was when the Society moved Rutherford to San Diego for 6 or more months out of the year.
Back in the days of the Staten Island Watchtower farm, the Society had a plot of land on the property of the United Methodist Church that was not far from the farm on Staten Island. That plot of about 100x100 feet was used by the WTB&TS as the final resting place of many of the Brooklyn family. No headstones were ever erected, but I have been told that at bethel there is a list of who is there. Judge Rutherford is supposed to be there, but he's not - an empty coffin is (Rutherford's body is in San Diego). W. E. Van Amburgh and his wife are there, among many others. I am not sure if cremation was used for some of the WT dead or not.
At some point in the 1950s, the Society began using plots located on the WT farm in Walkill, NY. Today there is a plot on the Patterson property, if memory serves.
I am sure that New York City and New York State have some clearly defined laws regarding when an autopsy is required, but I am equally sure that the WTB&TS is not above ignoring those laws when it suits them. There is a story about an Indian burial ground that the Society discovered during the excavation of one of their Brooklyn building projects. Reporting the project would have slowed down Jehovah's work, so it wasn't reported.
I leave it to others to flesh out (ha ha! a pun!) these stories, or to debunk them if they have facts showing otherwise.