Up to your questions:
- I would recommend to put the RadWindowManager in the master page. This way it will be available in all pages where you would need to open RadWindows.
- This will not be a problem because with RadWindow "Prometheus" you can have more than one RadWindowManager on the page. Note however that when you use the RadWindowManager's functions (radopen(), radprompt(), radconfirm() and radalert()), these functions will use the RadWindowManager which is first rendered on the page.
the Telerik team