Upvote:2
Travel documents : chances are, you need a Business Visa. You will need an invitation letter from the company or branch located in China. Check the website of your local Chinese Embassy for more details.
Money : always keep cash with you, most hotels and big shops accept Master Cards / VISA / AMEX, but others don't. You can easily take cash from most ATMs, personally, I had more luck with VISA than Mastercard (less common in Asia).
Phone / Data plan : its cheap, you can buy a SIM card anywhere (I recommend China Unicom, they have better 3G coverage, at least in Beijing). Then you can buy 50 or 100 RMB charge as you need, on the go.
In case of emergency, there are at least 2 international hospitals you can count on :
They are quite expensive, compared to other local hospitals, but its high quality.
Things to pack :
Upvote:3
If you're with a local I think you'll be fine already. If I recall correctly there's one international hospital in Beijing so you should be ok in case of any emergency. http://www.thebeijinger.com/directory/china-japan-friendship-hospital
Also it would be nice if you learn some Chinese as talking to the locals might be difficult. Learn just to say "yes" and "no" and count one to ten would be ok.
Be aware of pickpocket, always have your bag in front of you or you might have some surprise when you get home.
For the SIM card you can get that easily at the airport.
For the money, I suggest you to have some cash in pocket and when needed you can easily go to the ATM, e.g HSBC. Be aware of local banks as my friends used to get fake notes from the machine.
And try Peking duck. :-)