Tip: 2U is not advanced.
Depending on what university you want to attend will cause the ATAR needed to vary. I suggest you read up on the actual courses of ALL universities that you can comfortably get to, (yes, even UWS) to determine which course is right for you. All of them are 90+ though. (refer to: http://www.uac.edu.au/documents/atar...utoff-main.pdf for specifics)
Graduate entry refers to those who have already completed an undergraduate degree and wish to apply for a degree in Law.
Even if you don't get the ATAR you need, you can transfer into the law course after completing a year (or semester at some universities) in another. They don't always have to be related. You do need relatively good marks, though.