Re: empire total war campaign map and buildings
You couldn't mod that into ETW-map editing is pretty limited, though you can change a few things. Adding whole new towns is impossible right now.
Historically speaking, it was that empty. Most people concentrated in towns and cities.
Not true-pre industrial revolution the vast majority of people lived in the countryside, and that goes for all countries in the 18th century-all of them. There were large cities around, but not nearly as many as say in the mid 19th century, and they weren't that large by today's standards. (There were some exceptions like London, and other major capital cities)