Can someone please tell me what objects are in scope for CB Auto Action Type:Code?
No objects are. It's self contained for security purposes. If you need user data you need to use substitutions, which it will parse before executing your code.
Clearly we are newbies in CBPro and CBSubs, if I can get pointed to some docs, that would be great.
There is no documentation for CB Auto Actions as it's just a tool and what descriptions it needs are provided on the right of each input.
Going through the forum I see code such as $user = CBuser::getUserDataInstance( '[user_id]' ). So, I see the CBUser is there, but what else is available?
Anything you want. It just executes whatever you supply as PHP using either eval or create_function.