2. Remit Japanese yen into China account (highest cash exchange).
3. It is enough to have a bank card in China. You can remit it directly to your account in the Bank of Japan in China (you can do it yourself), and it will arrive in two or three days. I only know that the handling fee of 2 million yuan 1 10,000 yuan is 6000 yen.
4. The exchange rate between cash and cash is different, and cash is exchanged more.
For the rest, it is generally better to exchange them at the Bank of China. Great Wall Debit Card should be OK. Today's cash exchange rate is 6.9972, which has dropped a little recently. The highest time was 7.40 some time ago. Pay attention to the exchange rate of the day when changing.