Workflow or Workflows - Parameters/Artifacts communication

[amitm02]

The workflow of workflows example show how to pass a parameter from Parent workflow to Child workflow.

1. is there a way to pass a parameter the other way around, i.e from Child workflow to Parent workflow.
2. is there a way to pass as artifact from Parent workflow to Child workflow?
3. is there a way to pass as artifact from Child workflow to Parent workflow?