Ответ:

  1. She was worried because she thought the man might be a policeman or might be collecting information about her. She did not know that he was studying her accent.
  2. His confidence is shown by the way he identifies people’s origins from their speech and claims that he can teach the flower girl to speak like a duchess.
  3. Colonel Pickering will probably meet Higgins, discuss phonetics with him and become interested in his experiment with the flower girl.

Yes, I think the professor’s job is interesting because speech reveals where people come from, and studying it can help explain language and social differences.