Based on my previous experience, I found that:
1) paying by aussie CC (for hotel etc.) is the best in terms of rates in China. Exchanged in CBD exchange store for some cash, but not at a good rate! Any idea for cash exchange?!
2) Last time, bought China mobile sim, but could just use 2G data, as own iPhone 5 :( I'm not familiar with GSM bandwidth for sims/phones. has anybody tried/aware about China Unicom? Heard 4G works well on iphone 5.
1)try citi bank plus debit credit card. U can withdraw cash from most of chinese ATMs. Rates are based on current visa rates.
All cash exchange are rip off options
2) 4G data is avaliable, china mobile is the expensive option like telstra.
No idea about 4g ur iphone 5