I have been in this situation myself, The bad news is that from Australia, 30,000 Asiana points will get you to one destination only: New Zealand. It’s 12,500 points one-way on Air New Zealand in Economy, or 25,000 points return.
The good news: your points can get you to New Zealand! Why not plan a short stay or even a long weekend? There are any number of possibilities.
Is it possible to somehow book a leg for a trip in SE Asia or Asia in general?
Can’t really see myself going to New Zealand…
A question for you - would I be able to book a ticket using miles for Asia and then later be able to rebook the ticket? (i.e. book for X date and then change it to Y date when I know I’ll end up using it).
Can’t see yourself going to NZ? You don’t know what you’re missing!
The Asiana Star Alliance redemption tables are below (click on “South Pacific” as the origin). You’ll see that the minimum points you need to fly from South Pacific to Asia is 40,000 points one-way. So if you want to use the points for a flight, a flight to the South Pacific is the only option.
However, I was possibly being too limiting when I said that NZ is the “one destination” you can fly to. I haven’t tried this, but presumably you’d be able to fly VIA New Zealand to another destination that Air NZ flies to in the South Pacific.
Alternatively, you could book a paid ticket on Asiana and use your points to book other things such as lounge access and excess baggage (click on “Use Mileage” and then “Additional Services”).
I don’t know the answer to your second question but what I will say is that I’ve found Asiana’s customer service from their Sydney office to be very good. Give them a call and ask!
Adding on to the wonderful ideas from @sixtyeight , you will want to call them during business hours. I find that after say 5pm, it automatically redirects to their 24hr call centre in Korea where its the luck of the draw with the agent’s English abilities!