Re: changing rss url (redirecting to feedburner)
You could also use an .htaccess rule to do the redirect… something like:
RewriteCond %{HTTP_USER_AGENT} !FeedBurner
RewriteRule ^/forums/rss/$ http://feeds.feedburner.com/MyFeedBurnerUrl [R,L]
The first line says to redirect anybody but feedburner, and the second line actually does the redirect. You’d have to adjust the links there as necessary for your specific forum.
Of course this would only work for the main forum feed… you’d need to duplicate the lines for each RSS feed you wanted to redirect, and adjust the paths.