The writers responsibility would be to make sure that she has all of the information on her life. So I would think it may be good to have a few references from other people to help them with their timeline of their life.
The person writing this genre of literature usually is a known or famous personality whose life many people may have great interest or curiosity to know about. A biography offers a <em>general</em> content about their history, but the memoir is about a <em>specific event which might have details that only the person themselves is able to remember and inform,</em> or if there are other writers, the person knows better, and is the main source just because it's their experience (and their responsability of being true to their audience.)
answer: flight is a commonly used symbol most commonly to depict freedom or a wish to escape, as for the importance you can probably assume why slaves have dreams of freedom
