The way I am currently using it (on the new images I'm uploading) is that I put N/A if there are no people in the shot, but I put "No" against property release because that is such a changing environment. Strictly speaking every product has been designed and could theoretically claim some sort of copyright - similarly, rules can change about photos of landscapes or buildings. So I play safe and say "No property release" as my option.
The problem with turning it on later is how to do a default setting and not mess with the ones that have already been set manually!
Steve