The "keywords" meta tags is no longer used by any of the major search engines. Under some circumstances they can actually be scored negatively against the page rank, when a high count of irrelevant or duplicated key words are added.
The system will automatically de-duplicate keywords if entered. For example if "SEO, meta, Seo,tags,,," is entered as the list of keywords, the list will be converted to "SEO, meta, tags"
Later releases will deprecate the entry of key words completely. Currently Google completely
The XML is in the form
<meta name="viewport" content="width=device-width"/>
All child elements of the "head" element will be included in the generated page.
The page meta data can be set in the configuration tab for each page. All elements in the "head" element will be copied to the generated page head section.
The image meta data can be set in the "Appearance" and "Advanced" tabs of the image editor.