Hi.
I can only help you with a couple of your questions. If you need advice about entrance requirements etc, I would suggest contacting the uni.
I did UMEP biology last year, while also completing 5 VCE subjects (Specialist Maths, Maths Methods, English, Chem, German). I did 3/4 bio in year 11. I would NOT recommend doing this. Although you can bludge through most of UMEP bio (and pass), it still takes up a considerable amount of time (pracs, computer tasks, lectures, TRAVEL TIME..). I found the travelling to uni and essendon extremely tiring, especially in winter (when it's dark by the time you start the class). If you want to do really well, I would suggest treating it like a VCE subject.
However, I would highly recommend doing it as a 5th subject in year 12.
What other subjects are you thinking of doing?