maybe you activated a plugin which might conflict with our shortcode generator? Try to deactivate all plugins and check if the button appears again. The shortcode generator works in “Visual” mode only.
Yes – atm it’s only possible to use the shortcode generator in combination with the visual editor. The reason is that the visual editor uses tinymce and the shortcode generator is a plugin/extension for this editor. It will not work with the bbcode/html editor and it’s not easily possible to transfer it.