School violence in America

I am doing an applied program proposal which touches on school violence in America. I am planning an intervention program in early childhood education that uses a peer mediation approach. Before implementing this program, I need some basic research done. I need these questions answered:

1. What is school violence? What defines it?

2. What are the causes of school violence in America?

2. Who does it affect?

3. What are statistics and prevalence of school violence in america from early childhood to high school level?
What are the consequences?

4. What methods have been implemented to deter school violence? Have they worked? What has not worked?