Are you sure you can't check baggage all the way through? I've done it after arriving at BNE on at least 4 different airlines. Just go to the transfer desk, show the bag claim number, and they do the rest. Seems weird that it would require entering Australia only to check in again, rather than going to the transfer desk while in transit. But I have not had to do this myself so can't be sure.
If you did have to go through immigration and customs with your luggage, check in upstairs, then go back through the process the other direction, 2 hours is comfortable. BNE is not large and rarely very congested, and once you're checked in you're safe.
I called Virgin Australia, and I have seen a write up on experiences traveling to png. My question to you is, did they tag you baggage, on you original departure to go to POM. Or did the transfer desk do this for you?
Do you know if virgin Australia coming in from lax, and air nuigini are in the same terminal?
Appreciate your help. This trip is stressing me out.
Dustin