Having the FB page can be beneficial in that every time a user Likes something on your site, their news feed updates with a link back to what they liked. So if on each page you have a like button linked directly to that page, if a user clicks it, a message is posted in their news feed and those of their close friends (however FB determines who you should see updates from, another topic altogether).
So yes, if users are clicking the like buttons, it can help to drive traffic to your site because their friends are going to see that they liked your blog post or whatever and very well may click through to read the article or see the full size picture or whatever it was they happened to like.
Whether or not Google uses Facebook likes to determine your page rank, I'm not sure. I would expect they to use G+ data to do this at least a bit, but since Facebook got in bed with Microsoft, I'm not sure if they do or don't. It wouldn't be hard for a company like Google with their engineering team to parse out the likes from the DOM of the facebook page, but whether they actually do is something I cannot speak to directly. I'm also not sure if the links to any one site from Facebook are taken into account by Google for link backs in their page rank scoring system.
I always have like buttons pointing to the actual page they're on, when the user clicks it, it's usually because they Like the content of that page. I also use a Page Badge, or a Like Box in the side bar or somewhere clearly segregated from the like button so the user can Like the Facebook Page itself if they find themselves really enjoying the site and content.
