Remember that the people who tend to go to open days etc tend to be the nerds (i was actually helping with a booth so that could make me a super nerd haha).
It depends what you are studying. I would say if you are doing arts or education then there will be less asians. In commerce there are lots. Not sure about engineering and law... i think that would have more aussies but still quite a few asians. I have found the asians i have met to be good fun, it has not been a problem for me. However i do realise different course may attract differnet types of people.
Uni can be fun. Just dont think it will be like a american college movie.
I think most ravers spend too much of high school comming down so dont get the grades to get into unsw... i know there are a few floating around for you though.