why don't you just do the IB instead of the HSC then. that will give you a whole range of options including staying in Aus, British, and a range of other int'l unis.
it's definitely possible. i know someone who only got a state ranking for music 2 who got a 100. a non-state rank physics could get a very close scaled mark.
actually i have no idea where you live, i guessed it was around qld somewhere. i suppose it makes no difference whether it's 2 hr away or 2000km away, you still have to find accomodation.
generally med has been harder. with UQ provisional MBBS this year it might be different as I heard people with UMAT in the low 170s got in. however they could be BMPs i guess?