I really recommend getting hold of "Show Mummy the Money" it is a good starter book about setting up a business and the different things you need to know. It steps you through the process of working out a business idea is viable or not.

Generally you will need an ABN to business, wholesalers will want you to have an ABN before they sell to you.

Have a look a these parts of the forum, there may be a number of threads there that can answer a lot of questions you may have:

https://www.bellybelly.com.au/forums/working-home/
https://www.bellybelly.com.au/forums...ning-business/