Tours will be the most expensive item unless you fly around. Train fares are cheap and food is pretty safe from anywhere once you've become accustomed to it. But at the beginning the amount of oil in some dishes might give you dodgy stomach.
Beer in restaurants can be as little as 2.5 RMB a bottle. Here's the site I used the most during my 6 year stay there, I'm not kidding..6 years, but I would advise anyone to visit. Just watch your bags and pockets in crowded areas. I never had trouble but many have.

Most buses are 1 or 2 yuan flat rates in most cities. All the info is at this site, including rail, plane and bus times.

A small pocket phrasebook with Chinese characters is useful and will definately draw a crowd in some of the less touristy areas. Most students learn English at Primary school these days, and I taught a good number myself, so the younger people will be able to help you more than many more elderly folk, but some people are a bit shy to try using it.