Open World Mod. Possible?

Without a doubt I will try this mod once it's publicly released! I have been wanting at least an open neighborhood where my sim can just go where she wants without a loading screen.

I'm wondering tho if you can build/add your own houses to empty lots. And can you play rotationally, I thought I read on a tweet of his that this is basically like just one big lot. And if so, how would there be townies generated?