The visitor's questions were not an indication that he lacked the answers. Their purpose was to teach the gathering. Each question is concise, each reply is focused, and the sequence progresses gradually. The identity of the visitor is revealed at the end, illuminating the preceding conversation.
يُعَلِّمُكُمْ is a present-tense verb meaning “he teaches you,” with كُمْ addressing the group. The entire gathering benefited.
A useful principle for teaching is to frame clear questions, respond at the learner's level, and acknowledge when a matter lies outside one's knowledge.