1. Doors can only be destroyed on hardcore. And I already told ya that they were all intact.
2. They were gone by the time I finished the wall. But I made sure that at night they were safe by patrolling the village. All of them made it to safe places in time before mobs appeared.
It was actually creepy, as at first I noticed that there were a few less villagers than I remembered. Then one specific type disappeared, it was all before they were given trade powers though. So one time I decide to go on my first big journey through cave systems, that took a damn long time as usual, while I [unsuccesfully] searched for diamonds, and other stuff. So when I finally dig out of the ground, the first thing I see is rain. So that was weird, since the entire time I was playing and it was like 20 something days at that point, there was no rain. So I come out and head to my village. It's creepy, it's raining for the first time in that world and I arrive to my village and see that it's completely empty. I search house through house, it's night by then, it's raining and it's all empty, not a sign of a villager!
That's creepypasta material right here.
