Odd. Is your object scaled?

Tessellation only allow single values, not vectors such as Vector2

The question is though, should you be able to completely unlink displayed vs internal, or should there be a dropdown to select any of the preset internal names (_MainTex, _BumpMap etc.), while being able to rename the displayed one however you like?

Here's a checklist to get DX11 working:

• Are you running Windows 7 or later?
  
• Do you have a DX11 compatible GPU?
  
• Have you enabled DX11 in the project?
  

If the answer is yes on all of the above, let me know :)

Fog overrides should be provided in any case

Yep! Refraction is done in screen space, so it's using the same screen position data as the screen position node :)