Forum Moderators: Robert Charlton & goodroi
<priority> - optional - The priority of this URL relative to other URLs on your site...lets the search engines know which of your pages you deem most important so they can order the crawl of your pages in the way you would most like.[google.com...]
That said, it sounds like there may be some other issue going on, too, since the link structure within your site should also telegraph the most important pages to Google. Not seeing your index page is a major concern, although it should be indexed as example.com and not example.com/index.html
See Merging www.example.com/ and www.example.com/index.htm [webmasterworld.com], which is available in the Hot Topics area [webmasterworld.com] that is always pinned to the top of this forum's index page.