The feature is already available, but as we still testing it, it is still not documented yet. We can inform the detail on how to enable it.
Yes, a simple function is provided for returning back a value (ex. selected image url, etc)
Creating content block is by modifying a single html file called snippets.html (it contains html code for all content blocks which you can add/remove/modify)
Our email: builder@innovastudio.com
Thanks