Australian marrying a Chinese in China

Hi; I am Australian, my girlfriend is Chinese. We plan to get married in China (Hainan).
Do I need a Certificate of No Impediment to Marriage (CNI);
Should it be issued in Australia or through an Australian consulate in China
Does the CNI need any additional legalisation (authentication, notarisation, or apostille) and
Do I also require a 'Single Status Certificate'.

In Australia, the Single Status Certificate is issued at state level, and only applies to the state in which the certificate is issued; there is no national level Single Status Certificate.