I think some people here are misjudging the risks of this in different ways. No, this list doesn't let you identify or locate complete strangers. But it does let you look up the gun collection of anyone you know a little bit about. Don't assume a criminal can't search two spreadsheets just because you need help opening cat videos on Facebook. I have no data skills and I'm still able to pull information out of this way too easily. If an actual stat nerd goes through this and turns it into something more cohesive, then it'll be even easier to misuse.
Within limits, yes. Only the 2016+ dealer transaction list has serial numbers (and they probably are in there due to an error.)