As for your original question. Just like in JMVC, the controller bound to the DOM element will have the intance added to its data object.
So doing this:
- $('.child').data('controls')
will give you an array of control instances for that element.
The CanJS is more of an overview. You can find most of your answers there, but if you want the more detailed documentation (generated from the documentJS comments in the CanJS source) you can use donejs.com. Of course there is a lot of overlap between the two, so for high level topics there won't be much difference between the two sites.
Looks like CanJS graduated from being a TodoMVC labs project. I've updated the site.