On the whole undead thing, there are countless ways they can work. Just zombies come at least in varieties of necromantic zombie, spontaneous necromantic zombie, viral zombie and voodoo zombie. And there many ways to approach these. In short,
our souls are different.
Not that there's anything wrong about arguing how the undead are supposed to work. Personally I await with curiosity how exactly they are going to turn up in Dwarf Fortress. Judging from some of the power goals, we are going to have fun with them.
If golems turn out to be soulless, unalive blobs of clay/iron/meat not unlike robots, but still able to learn, I think it'd be really cool if it could "grow" a soul, some kind of ghost in the machine, over the centuries, gain some personality, and perhaps eventually really become a sentient being. And then set out on a quest to find the Fairy Queen and become a real boy. That is, if we are going to have golems at all.