if by nsw you mean unsw then thats a sick option, right in the middle of the city, do part time ski instructing down at the snowies too, you'll have a blast, i work at thredbo as an instructor and we have a fair few uni kids who do it part time
Seasons as in snow conditions? Well they are alright, lots of wet snow, and slush, and it doesn't last for long. Best places would Mt Hotham for steep terrain, Falls Creek for Park and Thredbo and Perisher for everything. There is not many options though in melbourne they are building a snowflex dry slope that will be mad and they might be building one in sydney so look out for that. http://www.skiingandsnowboarding.com.au/index.php
also for the seasons it depends what state you are in.I live in victoria, so in summer it usually is around 30 degrees celcius, and can often get to 40 degrees.
in winter its cold and wet usually around 8-13 degrees. And for the mountains the best ones are probably perisher, thredbo or falls creek.