This has been discussed before, however here is a short answer:
1. USyd and UNSW Law are two very good law schools, the law quality is pretty much the same. Note that prestige-wise, USyd is somewhat higher.
2. USyd arts is very good and well established and I would think it superior in philosophy and English, though those are the only two I have experienced at both USyd and UNSW.
3. If your focus is solely to become a lawyer, I recommend choosing USyd purely for the slight prestige advantage. However either one will give you the best opportunities to work for large firms.
4. The cut-off is based on demand, however sometimes universities adjust the cut-off (it has been suggested that there has been a little bit of shonky cut-off raising, but this seems to be just speculation).