Jacopo, I should be able to answer those questions, but it has been so long since I have touched it. But I am going to be returning to the land of the living soon - I am quitting my day job and going back to work on OFBiz full-time as of Jan. Tomorrow morning I am going to start a content management task, so I should be able to come up to speed then. I would be happy to work with you on any improvements to CMS.
I wrote the TemplateData.xml file - I think, but I can't remember where it was used. I will try to refresh my memory on it, but I think we would want to do future "templating" with widgets - since most of it will be dragging divs around. But then I have been away from it for a while. -Al
