Hi Ansileran,
First if I may say, I would look for a place in China that you like or think you would like. In my opinion Yunnan is great to live compared to other places in China. But not everyone may agree.
So if China is your place of interest, there is nor preperation to get you ready for it and I would do the leap over here. In the worst case if you don't like it you could always go back. If you plan to be a carer English teacher, than travelling being screwed over and going through some visa and cultural adventures is part of the business, at least in the beginning years.
If you look for a professional teaching job adding experience to your CV, I wouldn't recommend homestay for the lack of professional teaching. [According to what some peopel told me about it, so my input may not be accurate]. Plus to my knowledge they are somehat in a half-legal zone, so if you want to get all legal documents it's better to work for a school or an institute.
Option one: You find proper schools, international schools or go through headhunters or connections, usually those proper channels will use Skype interviews (if you offer to have an interview online, most HR guys will be happy to talk to you inline. plus the previously mentioned Video of your class worked for me in my last job).
Try to get a contract and documents handled before you leave France, if they send the proper papers you can already apply for the work visa in your home country.
The thing you have to be careful about is an agreement in China doesn't actually mean anything It could happen that they won't hire you last minute and to keep face not tell you until you arrive and even then just shut the door in your face.
PErsonally, I would go for option two
Option two: I would come to China on a tourist Visa [still one month Visa available in Hongkong with very little effort, plus flights from France should be cheaper than mainland cities anyway]. After arrival look for jobs. The new term is starting soon so most good positions are being taken as we speak.
anyway...
Once you got a job and if it's a good school and you have all the required documents you can apply for a Z-Visa, be aware though you need two years of work experience [pre July 1st requiremtns] disregarding what job [part time full time both valid].
So you got your job and let the HR guys tell you what to do to get the Visa.
There is an age limit too, I think you have to be at least 23 to get it and not older then 60 something. {Also here I am not sure about the exact age...a google run would bring clarity]
All in all it is not very hard as professional to get your Visa here in China and finding jobs is even easier. How easy it gets depends on how professional the employer is and how professional you are planning to be. Then, the sky is the limit.