1. I referred CMIS as experimental implementation as per your screenshot - this means we tested very specific scenario and only using the third-party libraries.
2. For SOAP binding the URL isn't end pointing to WSDL, we add something at the end of the URL entered to get WSDL itself
3. You need to select Repository here, but in order to do so you must SAVE rule first
4. Most likely you want to set Application configuration to use this repository to store Attachments, then you need to select root folder using read made Connect CMIS rule with Repository selected.
Having said that if you need to change GRS to point to different CMIS this most likely will require to redo pp 3 and 4. I would not assume we only changing some parameters ti some only-once generated code, but rather I would expect p.3 will go code generation again.
So, I do not see any point to have this feature at all as this will work only at very specific setup or with assumption each environment will point to FileNet instance which will have exactly the same structure - I would not expect this is valid assumption at all.