Hello,

As a new comer here I am answering a bit late to this post...
Yes the two first pictures are S. annularis and the last pic from Houchen are a bunch of S. annularis and O. rufodorsata.
The first species can be difficult to adapt to captivity and even if the set up seems perfect they can refuse to eat.On the other hand rufodorsata is a very interesting fellow and will accept invertebrates, fish, etc...
Sinonatrix is a genus which is very similar in lifestyle as the nerodia group...Always in the vicinity of water. Rufodorsata would be more like a thamnophis by nature.
Regarding their status and for answering to Houchen it is now forbidden to catch wild snakes in China...You can still find some people selling them on the market... but in big cities you need to know who sell them.