The problem of comprehensive threads is that it can be difficult to discuss a given aspect of the book without discussing other aspects. For instance, some of us suspect that kandra are related to hemalurgy because they're related to koloss, which have nails in their bodies. So in which comprehensive thread should that theory be discussed? (Hypothetically speaking; I actually have no more thoughts than the above to discuss on that particular theory.)
OK, got that little rant out, now it's time to humbly confess that my idea of kandra being entirely insubstantial, spiritual beings turns out to have been way off base and completely wrong. Wrong, wrong, wrong. I still think it would have been cool if it turned out that kandra not only were of Preservation, but actually WERE Preservation, but clearly that's not how EUOL chose to do things.
I still wonder how they can digest and excrete things, though, without a digestive system. (Didn't he say, when considering whether to make an eye, that organs without skeletons could easily be crushed by his mass of unattached muscles?) What IS their body made of, other than muscles and skin? Is there some sort of fluid?
Frankly, I think kandra are kind of gross and creepy. I think maybe that's what EUOL wants us to think. But I do like TenSoon; it looks like he's going to turn out to be quite a noble, self-sacrificing character.