definately should not be a consideration when choosing which uni to goto. as most ppl above pretty much stated, the majority of asians at unsw were born in Aus or have lived here a fair amount of time thus are Aussies considering most ppl immigrate here and are friendly, sociable etc etc.
international students... the odd occassions ive talked to a few nice ones (yes! in English!!), but sadly its a rarity. basically if you see someone with mutli-coloured stockings and attachments to the end of their phone that are bigger than their phone itself, its best to play it safe and head to the english side of the lecture/tutorial theatre/room.
environment? walk around campus (obviously not during hols..) and you may feel its totally... well fobby. but in reality it aint that bad, i think commerce is like 1/3 intl students? so yea, on the whole the majority of students are like any local students youd find at any uni