the only stats you really need to have memorised is current stuff (inflation, u/e rate etc.) + a few ones from different significant economic periods (e.g. COVID, GFC), the rest you can pretty easily BS
depends on the subject but what I did for memorising a bunch of eco essays is just walk around for hours while reading the essays (printed not on phone)
trust me UNSW law is not hard to get into at all, especially compared to USYD lol. u can get in with like a 94ish atar (probs even less) and average lat