Been given two bits of advice,
One, Australian credit cards don't work there, if so goes the Qantas travel card work?
and two injections are required (Hep and something) and malaria tablets
Australian credit cards work perfectly well in China whether for cash advances via any of the banks, or for point of sale.
The one thing to be very careful of however is dynamic currency conversion. Many businesses, including hotels and international restaurants/bars will automatically select you to be billed in Aussie dollars... even if you explicitly tell them you want to be billed in RMB.
sometimes you'll even get a credit card receipt to sign where they
seem to give you the option to select RMB or AUD. Unfortunately this doesn't often work... if there is an AUD equivalent printed anywhere on the receipt... even as a 'suggestion', it's likely the DCC will already have been done.
businesses will also tell you they don't know how to prevent DCC, or to 'take it up with your bank' or that 'we can't reverse' a transaction. Some of those may be true... it depends how well the business has taught its staff how to use the CC machine... but if you are at a big hotel, or restaurant catering for the western market, you should stand your ground. DCC can be very expensive (5 or 6% or more!)
The key is to always ask to be billed in RMB at the time you hand over your card, and at any time you feel like reinforcing the point while the staff are swiping your card and entering in the total!
I would check whether you need malaria tablets... you don't need them for beijing and I don't know of anyone taking them for Shenzhen. hep A and hep B would be good recommendations, they are you will need to discuss with your travel doctor to see if they will be effective by the time you travel.