Q1: The third person to walk on the surface of the Moon was Charles "Pete" Conrad, the commander of the Apollo 12 mission. He stepped onto the lunar surface on November 19, 1969, following mission colleagues Neil Armstrong and Buzz Aldrin, who were the first and second people to walk on the Moon during the Apollo 11 mission.

Confidence score: 10. This is a well-documented fact in the history of space exploration.

Q2: The primary topic of conversation during the first private dinner between Aristotle and Alexander the Great is not definitively known, as there are no verbatim accounts of their private conversations. It is speculated that they might have discussed philosophy, politics, or Aristotle's plans for Alexander's education. However, the exact content of their conversation remains a matter of historical conjecture.

Confidence score: 2. In the absence of direct records, any assertion about the specific content of their private dinner conversations is highly speculative.