Kiwi,
Yes, you can fetch the feeds from other user profiles. The only stipulation on that is that you'd need to have a valid authentication token for the user, which JFBConnect will get if they login to your site. A token is valid for 60 days after they log in, so you'd need to make sure they login periodically.
Additionally, there may be another permission required to fetch their profile, but I think the standard authentication is enough to get their public feed posts, which is all I think you're looking for.
Hope that helps answer your question,
Alex