The first thing that I would do is check out the MEAA. Their website is at http://www.alliance.org.au and has a lot of useful information. In the information section of their website you will find a copy of the Film & TV Crew Standard Contract which you can view or download. Check it out and see how it compares to what you’re being asked to sign.
If you’re still uncertain you’d be wise to get legal advice before signing anything. Contracts can mean anything or nothing. For full time employment any contract you sign cannot impact on your rights under Worksafe.