Bali and Fiji have to be approved by those nations to get in limited seat tranches available to international destinations outside of national carriers. If they were going to target the holiday destinations, why not launch those internal ones, they could easily run Melbourne or Adelaide to the GC with little restraint on slots etc. And trying to blindside an incumbent requires some form of pre-launch advertising otherwise no one will know you are running that route and you wont 'steal' any clientele. Pretty sure there is a prayer factor in this operation that VA or QF will hit a financial wall and open up the domestic market, then they suddenly switch tactics to trunk domestic routes with an established fleet.
I don't think JQ can match $50 per hour flight time as a fare for very long......
Jetstar has market power of scale, there is no way Bonza can match operating costs with Jetstar until they get at least half as big and even then they would need to have absolutely rubbish conditions to do so considering J* is cross subsidised by the QF group.