On to my next question. Let's say I'm to study commerce and try and transfer into law, is there an atar score which equates to the difficulty or even the effort to achieve an star score which equates to the difficulty of getting distinctions and transferring?
Not necessarily. ATARs reflect popularity and supply and demand (generally) so whilst the "good" courses tend to be the more popular ones, the required ATAR really isn't a difficulty indicator. As many of the older forum members will confirm, ATARs don't necessarily equate to GPAs either, it all depends on the work you put in.
Obvs going from a course that requires 65 to one that requires 95 might be tricky, but a lot of the content between subjects is the same, and if you're prepared to work hard there's no reason why an 80 should preclude you from an 85 course.
Cept VTAC of course.