I guess I prefer my fantasy a little darker - this optimistic production, somewhat utopic in nature, would not fit in my games. That said, in a more cheerful campaign, PCs could easily be part of the Royal Surveyors Guild, on missions to collect the information for this publication. Such an easy source of hooks to send them on any number of crazy missions for no other reasons than to see what is there.
This would fit in where your campaign had posted want ad's or adventurer's guilds.
In a small, genetically isolated region it is not uncommon for the locals to have three arms. The third arm is generally a second right arm that is a good bit weaker than a normal arm and is generally held against the chest. This hird arm is most often used to carry small things, though some of the more skilled craftsmen have learned little tricks with their third arm.