I am preparing a book which needs some material to appear like it is hand-written. I see many fonts available which simulate this look, however, I need something which also has hand-written fonts for both English letters and simplified Chinese characters, preferably with an open source or similar license. Where can I find such a font?
Although it's possible, you're unlikely to find a font you really like that has both English (Latin characters) and Chinese. Most font designers will design for one or the other and even if a font contains both, it may have poor quality Latin but good Chinese or vice-versa.
More realistic would be to find two separate fonts - a Latin one you like and a Chinese one you like - and switch fonts according to the current language (possibly even making use of font fall-back in whatever application you're using).
I'm not sure if this is considered advertising and all, but I get all my fonts from dafont.com. You can even browse on category/style. If I'm not mistaken, the free-downloadable fonts there are all freeware.