You need a bachelors degree to get a teaching job in China. This is one of the requirements for getting a working visa. Some schools may require a teaching degree or equivalent, but to satisfy the immigration requirements, the degree can be in any field.
Non-native speakers can get English teaching jobs in China, but the pay may be less than native speakers.
Most Chinese companies do not seem to be concerned about your experience and credentials outside of China. So if you have had several years of experience teaching in your own country, it will have little impact on getting a job in China. Having teaching experience in China, however, should be a good help in finding further work or a higher paying job.
South Africans may have a difficult time finding a job in China as there are many looking for work. Fewer companies are looking for South Africans, with a preference given to native speakers from the United States, Canada, UK, Australia, and New Zealand.
Be aware that it is common for black people to be discriminated against in China and unfortunately there is little that you can do about it.
People who are of Asian descent may also have trouble finding a job, even if you are a native speaker.
There are many agents and recruiters who will take advantage of you. Sign up with a larger, trusted agency.
The bigger cities such as Shanghai have a much higher cost of living, particularly for rentals, so if you are looking to try and save money, look for places offering a higher salary outside of the main cities, where the cost of living should be lower.