Mate, I cannot help with conversion info as I had a MECIR here in Aust before going to the US but the US requirements as far as flt training and flt standards go are basically the same as here on the test form.
You fly all the approaches you want a sign off on.
If you are thinking of training in USA The Practical Test Standards , ie PTS for any US licence or IFR rating has all their reqmts.
Airman Practical Test Standards (PTS)
You can download instrument PTS book from that link.
I would imagine on returning to Aust with a US licence and Inst rating you would have to do the IREX and possibly a flt test for initial issue of a MECIR here knowing CASA.
good luck.