This was mine task too in my ASL.
I was asked to answer first 4 questions so I am answer the first 4 questions.
1. I would help him / her by sharing his feelings and making feel lightened. After this I will encourage him / her to report in police and get the problem solved with help of cyber department. I will also make him / her sure to share his problem with parents because parents will be the most helpful part.
2. The main reason of his / her quietness is the fear of being scolded by parents and fear of loosing his facilities of internet. Then other reason may be the shame he / she has to face from others words and their sayings.
3. I will say him / her to share his problems with his parents and encourage him to go to the police in support of parents. I will give him / her some examples of people in similar situation and their courage to fight back.
4. The reaction of others may be positive as well as negative. Positive in such a way that his / her relatives, parents and friends as well as well wishers will support him / her to solve the problem. Negative in this way that some people me tell such things that will create fear of results and make him / her scared to take any step to solve the problem.
Hope you have got the best answer. If yes please comment and thanks.