You can get automatic bonus points for doing well in particular HSC subjects (WSU).
https://www.westernsydney.edu.au/informationabout/bonuspoints/subjectbonus/uwscourseareas/business/bachelor_of_accounting
Hope that helps.
Your internal mark does not really matter. Your internal rank and the relative gaps between each Extension 2 student are the most important factors. Yes, there still is a chance you can get an E4 :)