Hi there fellow aussie aviator.
To answer your questions about licencing conversion, the information given to you is incorrect.
I myself I have all australian rating, CPL MCIR, ATPL, but when I came to the US the FAA only credits you
1. Private pilot certificate and a multi engine endorsment
This is only a temporary pilot certificate and can only be used together with your aussie ratings. i.e must be current with a valid medical certifcate.
They will not credit you a instrument rating or an ATP
Here in the states it is called a certificate not a license.
Depending on how many hours you have, and type of hours flown, will depend on the type of training you will need to get a instrument, a commerical single, or a commercial multi.
If you have over 250 hours total then Part 61 is the way to go.
If you have between 150 and 200 then part 141 is the way to go.
I am a CFI/CFII/MEI and have done then for many south africans NZ and aussies.
The ATP is a joke. I did not even study for it and got 98%
If you would like some more detailed information email me. I would be more than happy to assist you in any way that I can.
fellow aussie aviator