I have a website that changes hourly, new contents are added from different feeds, so no original contents at all,
I have details pages where they show the details of every item, Then I have pages that link to details pages, they are overview of all the details pages, think about Ebay for example, you have places where you search and browse, then you can get into an auction.
So I thought since the details pages have a short life, I index and follow them while they are active, then I make them no index and follow when they become inactive.
In my sitemap I put the priority of details pages really low around .2 And the browse or overview pages since they are permanent and remain there forever have a rank of .9
The other problem I have is that the sitemap changes all the time, Google Webmaster tools seems to keep the older sitemaps, and it seems like I have to go resubmit the sitemap once in a while, why is that? why doesn't Google automatically re-read the sitemap?
So I have two questions here
1- Am I doing the right thing in the sitemap and the priority value, and no indexing short living pages?
2- Do I need to resubmit the sitemap every time it changes (that would be hourly) or every once in a while? I noticed I can call a url to resubmit the sitemap according to Google documentation do you think I should do that and if so how often?