Golfpro, in reality only a few students can get a UAI of 100, it's just not going to happen for 99.9% of the state (made up figure, but you get my point). While its good to have aspirations and goals, there's a difference between realistic and unrealistic. Your expectations of getting 100% in everything sound just a little too high, give yourself a break.
What are you going to do if you don't reach your 100% in everything goal? I remember replying to your other thread about repeating again - after you've already repeated once after completing it last year - so if you were considering that, it's fair to assume that you arent exactly heading for that 100% in everything for your HSC this year. Are you going to Keep on repeating the HSC until you go insane? Cause you will
Honestly, to me it sounds like you need to just get your HSC over and done with and move on with your life. You don't need to get perfect marks. Put it into perspective, there are much more important things.
I'm not having a go at you, so sorry if it has come across that way. I'm not saying you won't get really great marks in your HSC either! It's just that it sounds like you're putting way too much pressure on yourself. Have a look at the website of each university that you're interested in, they would all have different policies on accepting overseas applicants. If you're still unsure, you could always try contacting them. Good luck, I hope it all works out for you