2004-06 UAI cut-off for radiography was 89.00, and i THINK in 2007 it went up to 90 - don't quote me on that though.
Recommended hsc courses are either two of: chemistry, physics, biology. They're not pre-requisites, but very useful as you would have enough basic knowledge to grasp certain concepts. I didn't do hsc physics, did the bridging course (which was a rip) and still do alright with radiographic physics.
Job description: operating x-ray equipments, setting the radiation dose you're gonna use for the patient, positioning the patient/assisting them move onto the examination table. If you're working a night shift in emergency, you might need to help the doc interpret the images you took. But legally only radiologists (doctor) are allowed to report on the images.
Pay: first-year radiographers at private hospitals get around $22 and hour, whilst radiographers in public hospitals get $25ish. Theses figures are base rates, and do not include overtime, on-call rates etc. A supervisor at a regional public hospital told me that if you do get placed on-call, even if they only need you for an hour, you still get paid 4 hour's worth.
There are much more job opportunites as medical imaging is widespread, and radiation therapy departments are only available in a few centres in sydney.
Radiography is a 3 year full-time course, plus what we call a Professional Development Year. This is what you start off as once you graduate, like an intern year. In this year, you get trained in other diagnostic imaging modalities that u didn't get to learn at uni (but you'd know the theory already) because uni can't affoard to buy all the equipments for students to play with.
Australian Institue of Radiography (covers radiation therapy too)
link