What degree are you doing? Even if the workload for the one you're doing now isn't that great, combining two full workloads would be. What if you have exams on at the same time? You would have to explain the fact that you're studying at different unis which I'm pretty sure isn't allowed without...
Studentvip, zookal, depending on what uni you go to they might have their own site, macq does. But in saying all that, you're best off waiting till classes start to know exactly what you need, or at least checking your unit outline and seeing if it says it's a required text otherwise you could...
To be considered for the Main Round, changes can be made till midnight Jan 5, anything after that will be for the next round. That's why all the unis have their Info Days the day before or the week before, with iPads there so you can change your preferences easily.