Hello Alexandre,

please contact me at This e-mail address is being protected from spam bots, you need JavaScript enabled to view it providing access to backend site,
so i will be able to help and solve all 3 questions you posted here.

In the meanwhile:

-question with RSS-> due to a javascript code for Google Analytics incorrectly added to the XML of the feed, probably a bugged plugin?
-question with custom data source-> i should access backend to better help you
-question with sitemaps submission -> just submit the links to Google webmasters tools if you have an account in the section to submit sitemaps. Of course the HTML sitemap is not to submit, only the XML formats are to be submitted to search engines

Thanks and regards,

John