3.1 - check out/include Working Together to Safeguard Children, 'No Secrets' framework, Safeguarding Adults 2005
3.2 - think about what the Police do within their roles to protect those that are vulnerable, social workers, Care Quality Commission as well
3.3 -you could look at Baby P and how this is linked to Victoria Climbie, the failings are similar....or you could look at something like the Winterbourne view failings.
3.4 - this could include training, line manager/seniior collegue, national policies and local authorities.
I sugget you look at these suggestions and research them on the www so you have a better understanding of them too. I hope the above helps.