sub contracting question

Im a full-time employee for a company and i choose to work over 40 hours but just at a flat rate.
Today i have been told we can only work a max of 40hrs as they are now going to be forced to pay penalty rates. As this is going to impede my earning potential can someone run through the details and rules if i was to get my own ABN and contract my services to the company?
Obvioulsy i would charge a higher rate per hour to compensate for the loss of superannuation and holiday entitlement, but what are the rules regarding tax and how i pay it, and if i only make an income from that one source?

Any help would be greatly appreciated!