I think with USYD they'll only calculate your WAM if you are needing it to qualify for some programs (Talented Student Program for example)? Or ranking of exchange applications etc. But not an actual 'This is your degree with your WAM.' thing
Well a WAM is the weighted average mark, so you will have one no matter what, so long as you study at least one subject. Whether it is written on any official documents, it seems like it's been answered above.