In terms of adapting to terrain, I'm guessing you're wondering if it's always linear or if it can handle curves and such? It can do curved roads, etc. It can't generate a city, so you will have to draw it in manually, but they do have some tools to help with that (including a random building road setting, where you just draw in a road and it "auto-populates" it with generic buildings). There are also some good tutorials here that people have written regarding how to successfully learn and use CD3.