In the example answers below, I've underlined some of the phrases that examiners would like. They might seem easy to understand, but they are the kind of natural phrases that native speakers use. My answers are at band 9 level.
1. Why do you think sport is important?
I think sport is important for different reasons. For me, doing a sport is about having fun. When I play football, for example, I forget about everything else and just enjoy myself. Also, doing a sport helps you to keep fit and healthy, and it's a good way to socialise and make friends.
2. Do you think famous sportspeople are good role models for children?
I think that sportspeople should be good role models. Children look up to their favourite football players, like David Beckham for example, so I think that these people have an enormous responsibility. They should try to be a good influence, and behave in the right way.
3. Do you agree that sports stars earn too much money?
In my opinion, it's fair that the best sportspeople earn a lot of money. Being a top sportsperson requires hours of practice, and there are millions of sports fans who are willing to pay to see them play. If we don't want sportspeople to earn so much money, we shouldn't go to watch them.