The displacement of the voxels can also be done with a simple matrix transformation, as far as I see it; same like you'd do for the nodes in a 3d model, same as you'd do it with a 'traditional' 3d pipeline (OpenGL/DirectX) - unless I'm behind the curve and animation itself is done on the GPU nowadays, but I don't think it is.

Ragged boundaries wouldn't be an issue as long as there are enough voxels. What I understand, that's the whole point - you just have lots and lots of voxels, at a much finer resolution than you'd ever want to render at, so that you just (by brute force) render once without having to worry about anti-aliasing, gaps between planes etc.