How do you set up rss feeds correctly

I submitted my rss to feed burner. It looks like it is publishing the entire post. Is there any away to make it only publish the title and the first few sentences? Also which feed directories should I submit to. Does this really help seo?

RSS has little to do with SEO. It may help get some backlinks out there, but odds are your content will just be scraped. vb doesn't have an option to limit text.

So is there a mod that make the feeds into snippets?

You can check vbulletin.org for that. I do not know off hand.