NetworkLink support is there and should work (PreLeo: Please share some details), however autorefresh will not be part of v2.1 (perhaps in the future).
ScreenOverlay: Not currently possible with a GraphicsLayer (which the KML layer essentially is).
GroundOverlay & TimeStamps: It's on our list of possible future enhancements (post v2.1).
I'm not sure how you see Document and Folder hiarchy working on a graphicslayer. Could you share what you need this for / indend on using it?
Shortly after v2.1 releases, we will release the source code for the KML layer, so it's also an option to make those tweaks yourself.