Great questions actually. You do need to have your dealer create a room called My Home or Dashboard or whatever, and then add whatever you want to that room's screen.
You can add favorites to a room, they don't need to be "in" that room, but they need to be visible in that room's watch or listen menus, or in the case of lighting, you can click on "all rooms" to see lights and scenes from any room. If devices aren't visible, you can of course make them visible using composer HE, or have your dealer do it if you don't have HE. In the case of the "My Home" room, when you create that room just make everything visible.
hope that helps