Alex, those look like direct shapes on the generic model category, which can have a material applied during creation but are not editable or or modifiable in the traditional Revit Family sense. If you want editable families you will need to create and place Revit Families. This looks like a good candidate for an Adaptive Component Family.
As Japhy mentioned, the easiest way to add geometrical objects to Revit is to use a direct shape. It’s not a first class revit object, and assignment such as material is only possible as it’s created.
If there is a requirement that the objects be edited downstream from the user interface, then a direct shape is likely not acceptable. Note that there is an emphasis on the gg tools for revisions, so that if downstream changes to materials can be managed at source in Grasshopper, then the changes can be made there.
I’d suggest avoiding adaptive components where possible. The performance of the revit project if you have hundreds (or more) of unique objects is often not acceptable. But it still might be the best option. You need to create the adaptive family in this case and the points can be setout from grasshopper.
I’m not sure about the comment about floors, your image of the gh script shows the creation of a revit floor type and revit floor instances. What are you expecting if you use this component? It is intended for floors, not for facades.
But if you want to use Adaptive components, I’d suggest looking at Rhino Inside. McNeel have resources that we can’t compete with, you’ll typically find much more comprehensive documentation and hopefully some nice examples (I haven’t really tested this part of Rhino Inside Revit so I can’t point you to direct examples).