Is there a way to create a document template which includes custom data fields?

Question

Then I can use my Properties Mapper to make everything look the way I want with minimal clicking.

Answer 1

No, yEd currently does not support document templates.

The only workaround I can think of is creating custom properties in an empty document, saving the empty document, and instead of using yEd's "File" -> "New" action (or CTRL+N) always loading the previously created empty document.