Visa Questions - Hong Kong and Australia

Knowing that there are quite a few US ESTA sites charging for what is actually a free service, I need some guidance for a trip to Hong Kong and Australia.
My wife and I are going in August, having taken advantage of the deal yesterday, and we are both excited to be travelling to 2 places we have not gone to before.
As we are staying in Hong Kong for 3 days and we both have full British passports, i believe we do not need any form of Visa. Is that correct ?
With regard to the Australian Visa, I am confused as to where to apply for a Visitor's Visa, some places say $20US, some say 20, some say British passports cannot apply online, some say you can.
I don't want to go to the wrong site, and pay an the wrong amount.
Some pointers would be helpful.
I have tried the search facility here, and I started at the Australian Immigration site, but that was n't that helpful.
My wife and I are going in August, having taken advantage of the deal yesterday, and we are both excited to be travelling to 2 places we have not gone to before.
As we are staying in Hong Kong for 3 days and we both have full British passports, i believe we do not need any form of Visa. Is that correct ?
With regard to the Australian Visa, I am confused as to where to apply for a Visitor's Visa, some places say $20US, some say 20, some say British passports cannot apply online, some say you can.
I don't want to go to the wrong site, and pay an the wrong amount.
Some pointers would be helpful.
I have tried the search facility here, and I started at the Australian Immigration site, but that was n't that helpful.