Hey Funsocks, glad you like the game.
1. Currently, there are no NPC characters you can interact with in another way than combat. It's not a design limitation, more like resource limitation. Creating a meaningful interaction inside a roguelike (because of permadeath it can't feel too repetitive) is a considerable challenge. The scope of the game and my limited resources (at this time I'm the only developer that works on the game after full-time job) it was the first thing that had to be cut off to have a playable game.
Having said that. One of my goals with the game is to create a world that feels alive. It means improving the AI, so NPCs do more important stuff, build, interact with each other and so on. When a village is wiped out, it should impact other locations. It's going to be years of work to get to that point, unfortunately. I've seen many players would like to have their cult in the game and that sounds great to me too, I'll think about how to make it fun and fitting to a roguelike setting.
2. Currently, the goal is to wipe out everything. In the current alpha build the final location is on the mortal realm (Dreamworld and other gods are not implemented yet), although the game doesn't end when you take down the umm... well, spoilers. ;)
In terms of RPG, your view is one way to look at it. Consider this. You come to the mortal world as a weakened, forgotten god with barely any power left. You have no chance to challenge anyone in the Dreamworld anymore, so your only chance to regain control is to take souls from mortals. Even from a tiny rabbit. Souls are power. If you gather all existing souls inside you and take souls of powerful gods, what could you do in an empty world? You could start over, split your soul and from its parts create a new world however you like. Considering other gods will want to oppose you, there won't be much time for you to convince a couple of worthless mortals to worship you, they won't be able to help you. That's how I see it, but this story is not part of the game so that you can make your own, and I'll add as much flexibility as I can.
3. The world is 100% persistent. Nothing is truly gone until you salvage it. :)
4. I wrote an article about plans for the next three major releases, one of them is building. At this time, destruction in v0.3 is pretty much set in stone, but other two can be pushed back if you guys think there is something better that could have a more significant impact on the gameplay.
Thanks for the awesome feedback! :)