Hi Ryan,
Thanks for the feedback and raising the issues you’ve found!
I’m interested in the crash you’ve found, but we have made quite a sum of fixes since Preview 1 so your issue might have already been fixed.
As off now the Geometry Cache asset does not support an adjacency buffer which is required for the tessellation setup, in this case you could choose to import the animation as a skeletal mesh with morph targets (also a more compressed way of importing) which will support tessellation. 
I’m going to have a look into the materials issue and will report back to you with what I’ve found!
Cheers,
Jurre