Pictures are certainly supported in (at least) GIF, BMP, JPG and PNG formats. Make sure that the pictures are "local" to the document and not remote URLs.
By default, tables get stripped out. There's a check box on the "Settings" page (screwdriver icon) to control this. When you make the book, tables get converted to plain text.
Currently proofreading The Poison Belt, by Sir Arthur Conan Doyle.