1. Yes, SilverDox is now incorporated in the WebViewer product as the Silverlight component. In a sense, SilverDox is "rebranded" as WebViewer Silverlight and is now part of a bigger more complete product.
2. There are no major differences between SilverDox and WebViewer Silverlight. However, WebViewer Silverlight does has some extra features for working with JavaScript (i.e. using WebViewer.js to control the Silverlight viewer.) so that is why we recommend using WebViewer Silverlight.
3. We continue to provide support for SilverDox, but just as a part of the WebViewer solution.