Oki, regarding select object(s) by type this is a good example
For this you need to have the Civil 3D toolkit installed.
Instead of using the command line I would recommend run the graph from Dynamo Player instead of Dynamo which lower the steps for the users
And by using Dynamo Player you can have two graphs that are similar to each other but one select all objects of a specific type, the other one use the ”Select Objects” node from Civil 3D Toolkit.