Unfortunately, there is no documentation on RadControls for WPF, except the API reference that should be installed along with the RadControls for WPF. We will be preparing some additional documentation for Q2 release due on the 22nd of July. By then, you can start a new forum thread posting about any problem you face or a "how-to" question. We will gladly reply to you asap.
As for your second question - we will be launching RoadMap pages for both Sillverlight and WPF controls with the Q2 release. There, you will be able to learn about all our plans for the recent future.
the Telerik team