I’m really looking forward to hearing more about this too!
I’m not sure if this is a useful tidbit (or already knowledge in your endeavor), but when trying to get at specific elements within a symbol, the recommendation is to use a class name for those elements (as an ID would naturally collide when there’s more than one). Once you have a symbol instance that you’re targeting, you can then call code like:
var element = symbolInstance.element().getElementsByClassName("className")[0];
We added the class name in the identity inspector specifically for this purpose; the nice thing about getElementsByClassName is that it is a function on DOM nodes to restrict the scope.