Also, I am trying to automatically fill out a bill of materials table in the drawing template as well that would reference all the materials selected in assembly files.
When you go to link a property in a drawing, hit the drop down in the "link to property box. It will show you all the "codes" that are available for linking.
Play around with them maybe you'll find the one you need.
It also lists all the current custom properties you already have created yourself. For instance, all the entries shown below above the "SW-XX" ones are ones we created.
If you can't find the one you need, just create it and it will be here (reading from the part/assembly).
I forgot to mention you can link a custom property, "Material" for instance, to the material chosen for the part. I really don't think you can link any deeper than that into the SW material chosen, unless you create a custom property for it yourself.