Topic: RSS Showing different URL

I have 2 problems with the RSS feed of the forum

1. The rss feed of my forums is showing the different URL of topics, not the one originally created and upon clicking redirects to another URL, this way one single post have 3 different URL's

One is the original URL
Second is the RSS URL
Third is where the RSS URL gets redirected

It creates problems in SEO and Sitemap submissions, please share the solution.

Also, the RSS feed is not displaying all the items.

Please suggest which feed should I submit to Google webmaster tools as Sitemap.