Fortunately, no. RSS is updated on your schedule not free republic's. You can say how often you want to check for new material from 1 second to two weeks, free republic gets to decide how many new articles to send you, from 1 to 20 to every post since your last request. In Free Republic's case it appears to be the last 15 items to be posted. Unless you deliberately save an item RSS feeds aren't saved on your hard drive after you refresh everything.
So it's not really like mail at all in that the items are a lot more fleeting -- you most certainly will not get every post made on the free republic this way unless you go to extraordinary lengths to do so. But you can safely use this feed along with your other newsfeeds to have a consistant newsbrowsing environment that saves you from most forms of advertising until you actually want to go see the post.
I set up the free republic on my website feedreader (which is just a small personal page which the log files show as being blissfully ignored by the rest of the world) you're welcome to see how the feed actually would work in your browser and email. (Note the feed actually isn't refreshed until you hit the "up arrow" by the RSS graphic or if an hour has passed since the last update).
http://www.freerepublic.com/focus/f-news/browse.rss
Heh I guess it would help to post the correct link for the example of RSS newsfeeds and how they behave.
http://www.hunlock.com/news.php