The phone needs to be unlocked to use the sim card. Otherwise, you are going to have to pay massive roaming charges with your current carrier, if you can use the phone at all. Personally, since you are leaving so soon, I would get a cheap phone and cheap sim card while there in China just for use in China... unless you are planning on making many calls.
As for translation services, there are translating machines that can translate the spoken word for you. Since my lady speaks very good English, I didn't have the need for translation, so I'm not very familiar with any of the products. I'm sure there are people here that can give you more information about apps for your phone or a good machine to do the job, if that's the way you want to go.
