Thanks for all the posts, it really helped :)
Anyway, for closure, and also people whom might benefit from my experience, here's the summary:
USPS Priority International Shipment from USA (Montana) to Aus (Sydney):
Took 5 calendar days from time of shipment for parcel to be processed at ISC Los Angeles.
Took 6 calendar days after that for parcel to be have first scan-event in Australia (processed at sorting centre).
Took 4 calendar days after that for parcel to reach local post office; another day on top of that for delivery.
Events occurred over the course of Easter (may have affected delivery time).
Parcel was never track-able on Auspost's website; but a call to Auspost can help you ascertain whether Auspost has possession of it.
The parcel collection note the postman left in the mail indicated 5 days for collection, and only during business hours at the designated post office; however, I checked Auspost's website (or you may call them) if that post office had special parcel collection hours (e.g. open 2 hours before regular business hours purely for parcel collection) and it did so I could collect it early (since most regular folk happen to be busy working/schooling during regular business hours, making collection during that time unlikely).
[Also, I understand that the parcel can be held for a maximum of 10 days (working days I believe, but I failed to confirm this)]
Parcel required signing before collection.
I also used a third-party tracking site: www.trackitonline.ru (has more specific scan-event names and their explanations for their meaning (although it may get lost in translation); also leads me to believe these conform to a certain international standard)
Edited by EasySounds - 4/8/13 at 6:34am