the more friends you have on facebook, the more you may need to control the information flow coming to you via your news feed. you can control this by scrolling down to the bottom of your new sfeed (the default view shows the newsfeed) and clicking on "options for news feed."
you'll see a control panel of sorts where you can choose the types of stories you see, as well as specify which friends you want to hear from from, and which less. there is a link "how do i use this?" you may click on to get detailed information.
if you want to prune your friends list, you click on the "friends" tab, then click on "everyone." you will see an "x" to the right of the name which you can click to delete the person. they will not receive notification, so it's a "gentle" delete. (however, at some point they may search for you to send you a message and then they will know you deleted them--unless they're new to facebook, in which case they might think they accidentally deleted you and try to refriend you :-) )