When I looked at my archive for my Facebook, I wasn't expecting much. Joining in 2010, I've hardly done any activity besides messaging people, doing things for my groups, and poking people. I'll respond to a post someone sends to me or say happy birthday every once in a while, but otherwise my involvement on the site is very little. I never log into the account except when I'm in Madison or at home, so my IP address is always one of two series of numbers. I'm sure that if I looked hard enough, I could find all the posts I've ever made just by looking through my timeline. It was fun to see some of the conversations and how many times I've ever logged in, but it didn't seem like anything I didn't already know. It's always funny to see the ads on the sides for me only be about rabbits and video games, because that's the only things I've "liked" on Facebook.
As far as Facebook storing this information, I personally don't care what they do. I hardly ever use the site, so whatever information they have on me can be used any way they want. I can see some instances where some people may not want certain conversations or questionable posts to be seen by others, but under normal circumstances, the only one that should know about it is you. There is tons of information about us based on all the sites we go to, so Facebook is not unique in doing this. As long as you are responsible with your posts, then there should be no problem to worry about anything you do. In my opinion, then I don't see any problem, at least in my case, for the storage of this information.