Bob, you will get a range of advice on this forum. Only you can decide if the advice is worthwhile, and for you it should be based on what you think you need for your work and personal development as a teacher, and not just the unique nature of China's education system. By unique I mean that people are employed from a range of backgrounds, experience and qualifications.

My previous experience in teaching and training in the UK included over 3 years in a college English department. Even if one has a degree in teaching English language and literature for example, it will not provide adequate preparation for teaching English as a foreign language. In the UK some qualified teachers are doing the CELTA and DELTA courses because in some inner-city schools there can be as many as 14 different languages spoken by pupils. So teaching English to non-native speakers is obviously not the same as teaching English to native speakers. The methodology is different in many ways but lesson or stage plans can share similarities.

There's little doubt that experience is very important. If you don't have that experience, than accredited TEFL/TESOL training courses can provide a good foundation. In training parlance, getting another teacher to help you is called "Learning from Nellie." If you are lucky and get a good Nellie they can guide you. However,if you are unlucky but trusting, you may learn approaches that have no pedagogic foundation. Remember that all of these TEFL/TESOL courses can be part of your journey and not your final destination.

All four universities where I have worked in China provided textbooks and AV. Some of these textbooks were/are excellent, others are replete with errors. The computer software used in classrooms is often full of viruses. My current university was established several decades ago, and although the School of Foreign Languages building is the oldest building on campus, all classrooms in this building and across the university are equipped with a computer, LCD projector and screen. That still doesn't stop the "Death by Powerpoint" syndrome where the use of the technology for its own sake, gets in the way of the teaching. However, apart from one classroom used for teachning Chinese, our language labs have been removed. I'm guessing the reason was that the cassette-tape based systems were getting old and expensive to maintain. (I use a good quality portable CD player provided by the School, which has an input for MP3 audio files).

It's also true that teaching is a very practical skill and one should get better through experience. This depends to a large extent on whether a teacher reflects on their current practice and disgards things that don't work. Some people can adapt and manage the learning environment very well whilst others need a stronger foundation. Having done some voluntary work in a deprived rural school with few facilities, it was not as challenging as I thought it would be. Often the use of AV can be nothing more than a crutch, because good lessons can be achieved without the technology if the purpose is clear.

I only have experience of the CELTA programme so cannot comment on other courses, but there is now an online option if your circumstances are such that an online option woud be better.