Your child doesn't need to learn olympiad. It's all from China. It's useless. It is completely harmful to children. Mathematics abroad is very simple and easy to use, and you won't learn anything you don't need. You can take Four Treasures of the Study with you. It's hard to buy here.
There is no need to bring new concepts. There is a language environment here, and English learning in China is also very impractical. Pay too much attention to vocabulary and not too much attention to application. Books really don't need much consideration. The information on the Internet is all new, and it doesn't take up space. Many books were compiled years ago.
There are also some daily necessities, and there are many Chinese supermarkets.
Mobile or Unicom cards are used in China, but they can be used in Australia. The mobile phone model in Australia is GSM+WCDMA+LTE. You can buy a card directly when you get off the plane, or you can apply for a GSM card. To be honest, the mobile GSM signal is very good, better than any telecom company in Australia. You can buy some mobile phone company's mobile phone cards when you get off the plane, and you can buy optus's.
You can sign a contract with a telecom company in the future. In that case, I suggest signing Telstra. The signal is better, but other companies are not so good.