negotiating without broker

I'm putting my ducks in a row to make an offer on an fsbo, not using a broker myself. (Have a good lawyer and mortgage pre-approval.) Negotiating info on other threads here has been very helpful. Some questions: 1--I'm browsing acris and don't know what to look for or even quite what I'm seeing when I call up a document. E.g., one document that seemed very significant at first in the end seemed to be only about where the water bill should be sent; but I'm not sure! Any tips on using that site would be welcome. Or point me to self-help site. 2--Owner paid 455k in 2004, 1 bedroom UWS above 96th, West of Bway, non-dm, well-kept mid-sized bldg, unrenovated apt. Asks 550,000 but has said will accept 525k. I want to offer 500k, or less. Thoughts?