I agree with the original poster. This is a very basic and fundamental piece of information that cannot be found anywhere. How can we use this great software without understanding all the naming conventions. You mention keywords that trigger certain things, it would be helpful to know this.
> - the complete list of keywords and how they can be combined with other words
See the full documentation here: https://forums.adobe.com/docs/DOC-5977
We're also planning to create a "cheat sheet".
> - what is allowed in hierarchy and what isn't
You can have as many layers and as much hierarchy as you want. The extra things that Ch doesn't recognize should just come along for the ride (e.g. Ch doesn't look for an "arm" layer, but you can have one, and if so, you'll see it; if it's on the same rubber sheet as the Head, it will move along with the Head).
> - how does hierarchy of layers affect animation: e.g. do hands and legs have to be children of a body layer?
There are no restrictions per se, but different hierarchies will give different results. The simplest layout is everything on a single rubber sheet (i.e. no "+"/Warp Independently subpuppets). But that's not always the look you want.
> - can "Mousetrack" and "Fixed" elements be in the same layer or group?
Yes -- though if they are too close together you'll see extreme stretching of the Mousetrack handle as you pull it away from the Fixed handle.
> - what about groups and layers - does it matter if it's a group or a layer?
> - how does "Fixed", "attach", "Origin", "Mousetrack" etc. work - do they need to be part of the group or layer their object is in or do they just work by position or by name?
Fixed means the handle should stay in place even if other handles on the same rubber sheet (Mousetrack / Head / etc.) are moved.
attachTo is a special command on group that lets you attach it to a particular handle -- otherwise a group is always attached to its parent's origin.
If you don't specify an Origin, the origin for a group is assumed to be its center. By specifying an origin, you can, say, attach a stick by its end rather than its middle.
handles with Mousetrack in the name can be moved with the mouse (the nearest one is grabbed)
See the doc link above for more details.
This is still all quite complicated, which is part of the reason we're only calling it a "Preview" release, sorry about that.
If you have a PSD or AI file that's not working and you're willing to share it here, we'll try to fix it for you when you have a moment.
Thanks so much.