Re: New thought with my subjects (Preferably ex or current USYD students to answer th
While you will have to check on each university's specifications, you should be allowed to do units at other universities, and you can apply for credit at USYD to have it count towards your degree. However, the units themselves you will have to do via non-degree study (unless there are particular arrangements between the two university's faculties), which would require you to pay the tuition fees upfront. So no HECS unfortunately.
Also it's worth noting that, at USYD at least, the tuition fees for Summer School subjects are deferred to FEE-HELP instead of HECS. In reality FEE-HELP is pretty much the exact same as HECS except with a lower limit on the money you can defer. So while you won't have a HECS debt for those subjects you'll still have to pay the same amount of money back through a different scheme.