Russell and Jen,
"Inc" is for incorporated body and is the correct term for an incorporated club or association - this is the usual method for clubs (its done at a State level)
Here is a Vic association Rules template
http://www.consumer.vic.gov.au/clubs...es#model-rules
Pty Ltd is for a private trading company which has directors and shareholders - this is Federal and done through ASIC
I believe that a Society can be slightly different to an incorporated asscociation or it can be the same - but I dont have any detail
You can remain unincorporated as just a general group of friends but its worth understanding the problems, limitations on owning assets and the personal risks
http://www.lawhandbook.sa.gov.au/ch08s02.php
Good luck Jen - sounds like its all coming together.