2. DX11 AND DX10 has tesselation, frankly i dont know what DX11 does that DX10 doesnt do in civ5. Maybe depth of field or something?
This is completely incorrect, DX10 does NOT have tessellation. This was implemented into DX11 cards, and even if DX10 manage to support it, it would not be able to run it as none of the DX10 cards have dedicated tessellation processing like the HD 5000 and GTX 400 range does.
Do your homework on DX11, DX10 CANNOT even run this:

Its funny that DX11 and Tessellation are working so great in Civ V, but as usual, tech noobs on the forums are quick to write it off as something that is meaningless and would work on older hardware when it absolutely wouldnt.