Hi! I'm travelling MEL-SYD on QF 187 economy class. QF 187 will continue to HKG from SYD as an international flight. I'm OW Emerald (Finnair Platinium). As this is a domestic flight, can I have access to QF lounges and if I have can have acces to First class lounge.

Also any information, is it possible to upg this with using cash and is it worth it. I'm travelling on N class ticket.

And, where should I check-in. First class international???