The work poermit does not come because you have a residence permit for whatever reason.  The only way to work legally in China is by having a work visa stamped on your passport.  Once you enter China with that work visa, it will expire in 30 days and you must obtain (or finish the process to obtain) your FEC, have a health check, obtain a work permit from the Labor Bureau (and now you can legally work), and a residence permit to allow you to live in China while working.  Also bear in mind, makes no difference if workinbg for an employer, or in your own business, you do need to do this, but the work visa, work permit, reisdence permit and FEC are all tied up with whomever your employer is, and you can only work for him, no one else.    Assume you work teaching English at one school, with that work permit you can not open a bar, or a grocery store, or work for another firm LEGALLY !.

What I was thinking about in terms of free-lance work is private English lessons, as I have reached the age where I would not be hired by an institute.  A school will not offer insurance after age 60, the Chinese retirement age.  I would like to see the requirements for the FEC. You are saying it is given on the request of the language school.   I have seen suggested that small entrepreneurs attach themselves to a business organization that hosts all sorts of  diverse activities.  They apparently exist.  One ambitious alternative would be to form a private English instruction business.  I have seen the requirements for starting a business.  I don't know if they are always the same.  A teaching business would not require a lot of start-up capital, though the Chinese might require it anyway.  Of course, I could always layback and be a happy bum in the tea house.  Why should the practical concerns of life bother me?

Thank you.  I see more questions I need to answer.  Like the requirements for the medical exam.