I actually have two Facebooks. My main one is the one I've always had under my longstanding nickname. It's pretty much limited to close friends from high school and college that I don't want to lose contact with. It's where I rant about work and life and share things that I think my social circle might find interesting, and occasionally a politically charged post (but I avoid that normally since I find it annoying and assume others do as well).
My "professional" Facebook is under my real name. I started it when I graduated, and it's part of my professional "brand"(LinkedIn, my Web site, my portfolio, etc.). It's also a red herring to draw people away my main account. Family, co-workers, people from professional associations, etc., all go on there. I curate my posting much more carefully--nothing political or religious, nothing that could get me fired, etc. Lots of personal information, but nothing that's not already on my Web site or my LinkedIn.
My rule for both is that if I don't know you in person, I don't accept your friend request (with some exceptions for VERY close Internet friends, many of whom I've subsequently met in person).
I'm not worried about my personal information getting found because I know it's already out there. I was part of the OPM breach, so they already have far more information that I put on my Facebook page. I'm anonymous on this site for the same reason many others are: it's a safe zone where we can talk about pretty much anything, including our personal financial situations. Posting under our real names would jeopardize that, and I sure as heck wouldn't want some of my posts from here to be indexed by Google under my real name.