As a never-signed up non-member of the FB empire, how do I find out what they know about me without them finding out even more?
It's funny you should ask that.
You know those services that you can pay to have all your internet traces erased. You know the ones. They don't know you exist and then you contact them and they start searching for you using highly sophisticated techniques that analyse your writing style and even track down the aliases you wrote under and have long since forgotten and pin it to the walls, like in a Police Incident Room, and look at it and say "That's a lot of very revealing information that nobody had bothered to link and draw the lines between before; it'd be a shame if
anything happened to it got into the public domain. Oh, by the way, we also have your bank details now as well - thanks for that."
No, I've never used one either ; D