First off, congratulations!
The goal for this question is to get the origin and axis of the Revolve form for further processing. Let’s say, for placing some geometry at the origin and orienting it according to the axis.
The family (as opposed to the instance) is accessible in Dynamo. So a relevant question is how to get the Revolve form from the family itself. Looking at the Revit API, GetSubelements seems to be the only candidate for getting the objects out that make up a family. Q3: So I suppose a form (revolve or other) is a Subelement of a family, right? I haven’t found a Dynamo node for doing that though. This post discusses Get subelements, although using Python script. Q4: is there a Dynamo node for getting the subelements of a family?