The Australian government website contains a range of information for those who wish to enter the country on a temporary basis, and you will find answers to many of your questions on their site.
Please check your passport is valid before applying to become a hosted buyer. As we’ve seen around the world in recent times, there are long delays to have passports reissued. The Australian government does not impose six month passport validity for travellers entering the country, however, some airlines insist on the validity as part of their terms and conditions to board a flight – please ensure you have checked this.
Please check visa requirements for entering Australia on this site - visas are dependent on which country issued your passport.
From the list on the government site the main purpose of your visit is ‘attending a conference or expo’ which is about halfway down the list on the link above.
Visas applications must be covered at your own expense, and you should apply once your hosted buyer status has been confirmed. Please be advised that, due to high demand, visas are taking longer to process and can take months in some cases. Please book early to avoid disappointment.
If you require a letter to support your visa application, please advise the Hosted Buyer Manager ASAP.