Will we need a Transit Visa and which one?

Dear Sir,

My family and I all hold an Australian Passport each and we will be traveling home to Australia from Japan.
We will be arriving at Shanghai Hongqiao Airport with Japan Airlines and have an 8 hour Layover.
However I did not realize that we needed to travel to a different airport, Shanghai Pu Dong Airport where our next plane will departure for Australia.

What is recommended for someone in my situation?
Do I need a visa, if so which one? or can we use the 24 hour free transit?
Also it there a bus that travels between the two airports?

Thank you so much.