My family and I will be traveling to Taipei from Sydney, with transit in Haikou in 10 days time.

I have just been informed today that our return flight on China Airline from Taipei to Haikou on 2 Oct has been cancelled. It has been changed to 30 September. But our flight from Hailou to Sydney by Hainan Airline , on 2 Oct has not changed. So we will be required to transit in Haikou for 50 hours waiting for connecting flight back to Sydney. We hold Australian and Malaysian passports. Would appreciate advice on the following

1. Do we need a Visa for transit in Haikou for 50 hours?
2. If so, what type of Visa is required?
3. Does it need to involve an agent?
4. What document(s) is required for the application?
5. What is the cost for the Visa and how long will it take.

Thank you and would be grateful for any assistance on the above.