Hello, if you need to list Type parameters, you will get them from the types of the elements, and not from the elements themselves. Try to insert an Element.Type node in between. You should also verify your Element.Parameters node to see if the needed parameters are listed.
I can also see the FamilyInstance.Symbol node in the Primer (http://dynamoprimer.com/en/08_Dynamo-for-Revit/8-2_Selecting.html) but I can’t actually find it in Dynamo 1.2.1.3083. I found this update about it:
How to find node:"FamilyInstance.Symbol "