Firstly I would disagree with anyone who says that salaries in China are not enough to sustain a comfortable lifestyle. As long as you have a look around and find something that is paying at least 5000rmb a month you will have a hard time spending yourself broke before payday and i assume that at the your age you would have seen enough in your life such that you probably wouldn't be needing to go in search of new social experiences on a nightly basis. (That would probably put one over the 5000 a month budget depending on the types of establishments one might be drawn.)

Secondly,as long as you are hale and hearty your age should not be a factor at all except perhaps for the occasional startup language mill who might be seeking youthful beauty over anything else to be used as bait with which to lure their clientelle. In fact, contrary to your worries, I thing that many institutions such as universities and schools here do tend to value the stability and patience that develops with maturity over the flightiness of youth, though anyone who has spent any time in a high school classroom here would probably recommend a university position as the best choice.