I achieved my bachelor in science from NTU (National Taiwan University), a top school from Taiwan (like yours from Australia -you're from the University of Sydney right?). Many people claim that most schools won't accept foreign credits, but it's not true. There are many international students with accredited colleges (usually those on the top 100) whose courses can be waived into being accepted.
The only thing is, AMCAS (The Med School Application Services) won't give you an AMCAS GPA or an AMCAS verified grade, which means they don't want to take responsibility. They'll process your application saying your grades are "not intended to be verified by AMCAS" and they'll leave it up to the schools to decide whether or not they'll accept you based on those grades.
MOST schools say that you must complete 2 hours of undergraduate studies in the United States, but there are plenty of talented international students that are given entry into their school based on their multi-cultural experiences and outstanding performance on their MCAT. So if you must apply without post-bac, you have to make an excellent list of work/activities, AND you must tell them what qualities would make the school interested in you and only you, and why you stand out from all the other 100 million international applicants XD.
And if you choose to do the Post-bac, then yes, they're counted in your GPA. But choose your post-bac schools carefully. Some are hell.
Btw, try not to bump threads. Otherwise, we'll think you're trying to spam, which I know you're not. =)