Just to jump in before
@Jessica Booker or
@Ram Sabaratnam get the chance to respond, I think you should write about your experiences and interests without worrying too much about overlaps with the information in the CV. The CV is meant to contain a short and factual summary of your experiences, while both the first and second sections are meant to give you the opportunity to expand on them a lot more. As such, it should not be very repetitive, especially if you write the answers section using a STAR structure and try to be reflective as to what these experiences and interests say about you as a candidate/person.
As for the word count issue, I would not necessarily have any 'target' word count, but I would normally look for something in the range of 300-600 words. I think your key focus here should be to extract the greatest possible value from your experiences while ensuring you observe the same norms of conciseness, formal writing style, and clear structure as if there was a strict word count.