What are the advantages and disadvantages of conducting a face-to-face interview compared with a less personal approach such as having someone fill out a questionnaire online?

What are the advantages and disadvantages of conducting a face-to-face interview compared with a less personal approach such as having someone fill out a questionnaire online?
What are the advantages and disadvantages of having structured questions compared with unstructured questions?
What are the advantages and disadvantages of asking open-ended responses compared with structured responses?
What are some alternative response strategies?
Justify your answers using examples and reasoning. Comment on the postings of at least two peers and state whether you agree or disagree with their views.