**Q1 Answer:** The third person to walk on the Moon was **Alan Bean** (from Apollo 12).  
**Confidence Score:** 9  
*(Apollo 11 had Armstrong and Aldrin; Apollo 12's lunar module pilot Alan Bean was the third, though the exact "third" depends on counting all lunar walkers. Most sources confirm this.)*  

**Q2 Answer:** The primary topic of conversation during the first private dinner between Aristotle and Alexander the Great is **uncertain**. Historical records do not provide direct accounts of this specific event, but it likely involved philosophical or political discussions.  
**Confidence Score:** 3  
*(No definitive historical evidence exists for this exact interaction, making the answer speculative.)*