1) We would recommend wrapping the fuctionality you need in a user control and place it on all the pages where you need this functionality. An alternative would be to place the Generic Content control on a template and select this template for the pages where you would need to have the functionality.
2) Yes, you are right about the Polygon feature. It was disabled in this particular version of RadEditor.
In the current version of RadEditor Prometheus it is removed altogether (so the choice is limited between rectangle and circle areas) and we don't know when it will be back. We'll notify our RadEditor team about your request.
Do not hesitate to contact us again if you need any further help.
the Telerik team