Here's a few good sites that might point you to the information you need:
Carers Australia
For information about what Carers Australia does and links to carers associations in each state and territory.You'll be able to find useful fact sheets and links to the Carers Association in your state.
Reach Out
A national website for young people on issues that effect their lives.
It's All Right
Was put together by SANE and can give you some information and links about mental illness. It's pretty funky and easy to read.
Kids Help Line
Has some information about bullying, dealing with stress and talking things through.