1. The last 3 elements on the URL represent the NodeRef (protocol/store/id) to the item you wish to navigate too. So if you are using a different store, then yes you will use a different NodeRef so a different store in the URL.
Do you want to access content directly? If so you want to copy/paste the download URLs from the web-client that use the download servlet. These URLs provide direct access to the content itself rather than a JSF page: http://www.alfresco.org/mediawiki/index.php/URL_Addressability
2. The generated RSS file is the output from the template itself. So if you are using the template servlet then you will receive the RSS XML as the output from the servlet. You can only really use the RSS template in this way at present.