Questions:
What is the least expensive way to spend money while staying in Beijing for 7 weeks: US Traveler's Checks exchanged for yuan at bank? OR credit cards? OR using ATM's at banks?

What is BEST & least expensive way to use US cell phone in Beijing? Replace US sim card with Chinese sim card? (how much does that cost?) OR buy disposable phone in Beijing? (where? how much?)

Please answer as soon as possible. I go to Beijing soon.