I have just gotten off Rhapsody on the South Pacific run. I was in outside cabin 3064 on 1 Feb - 11 Feb 2013. So to answer a few questions.
All islands accept AUS Dollars.
Noumea & Lifou local currency is French Pacific Francs
Shore excursions are only offered in Noumea & Vila from RC.
Noumea you dock at a working port & you will be shuttled into the tourist centre.
You can ride the tchou tchou trains(green) cost $30 each(about 1 - 1.5 hrs) with 3 stops and includes the hop on/off bus for the rest of the day
You can book the tchou tchou train (yellow) from RC $55 and collected from the port and has I believe 5 stops.
We tried the Mcdonalds in NOumea & found it to be expensive.
We found Noumea to be a dirty smelly port if cal and the locals not that friendly.