Could you please add standard info about meta data in this article

I would like to know information like

  • Best Cover image size
  • Background image size
  • What kind of elements the XML file can handle
  • Are there any Attribute on the elements in the xml file we should know about.
  • What kind of names can i put into the type attribute of the media element in the xml file.
  • and so on...

Generally i would like to have the standards pointed out for me about the media player and the metadata.