The only NPCs within the town, perhaps the entire world, are the four Caretakers. They only interact with the characters over the communicators or an intercom system. Other than that, characters will find no natives, only whatever they left behind before they died years and years before.

As for supplies, they do not restock. What characters can find available to them is finite. So the food, ammunition, and medical supplies that they gather is all that they will get from this one particular place. When that runs out, they'll have to rely on the land.