Not yet implemented. Although we plan to implement the ImageData functionality the RWT developer needs to be aware of the fact that the image manipulation takes place on the server-side. To display an image in the application (browser) it needs to be persistent and accessible by a link to the server.
Image is implemented, but with a different API. The RWT image references only the path to the image.
Unlikely, apart from animated GIFs;)
Not yet implemented.