Hey Rathin,
I am a 2015 recipient of the E12 Access Scheme for the 2016 intake of Bachelor of Applied Science (Speech Pathology). To answer some of your questions:
1. No, not everyone who applies for E12 gets an offer. The E12 program is one of USYD's ways to diversify the student population (as through E12, Sydney Uni is able to get some high achieving students from low socio-economic schools across NSW). There is a considerable amount of people who are interested with the perks that come along with E12, together with a conditional offer before HSC (which to be honest was quite a relief), an iPad, mentoring and an access card amongst most things. For Physio specifically, I had two friends apply for a spot. Both of them didn't make it in (despite good grades and a solid application).
2. If you are selected as one of the candidates that get a conditional offer before HSC... then yes, your cutoff will be 85.
3. Physio is very competitive (although E12 is competitive for any course you apply to... some more than others). Since you're just in Year 11, just do your best and work hard... especially since to get e12 you need your principal to recommend you. Make sure you have a positive reputation with your teachers so that they can also put in a good word for you (as the Principal may ask staff for some info about you). The online application also is integral to your acceptance. It will get you to the next stage of the application process... (I think physio has an interview).
Best of luck. If you need help writing your application when you're in year 12, shoot me a message