If you are not an Australian citizen, you can only borrow 80% at most.
What is the minimum down payment?
For developers, the down payment is only 10%, but for bank loans, you should make sure that you have the remaining 20% of the funds, as well as the money to pay stamp duty, legal fees and so on.
The current lowest interest rate seems to be around 3.8%, which is very low. It is better to repay the loan with a fixed interest rate.
At present, the average floating interest rate is around 5.8-6. 1, which is not as low as you said. The fixed interest rate is indeed lower, reaching about 5.7-5.8. However, if you want to ensure that your interest rate will remain unchanged from the moment of application to full approval, you need to pay the fee for locking the interest rate.
What preferential policies can 4 PR enjoy when buying a house?
At present, the preferential policies for buying houses in Australia are mainly aimed at Australian citizens, that is, holders of Australian passports, and the current preferential policies are only aimed at buying new houses, not second-hand houses (the preferential policies in New Jersey include a subsidy of 15000 Australian dollars and exemption from stamp duty).
Are there other miscellaneous things besides the house price?
On the whole, there is no other trouble. Find a good lawyer over there who can help you, including making an appointment with the bank at last.