Can I use materials to improve these terrain meshes?

Development Rendering
1

Hi, I have some large terrain meshed taken from CAD programs that I am trying to get looking good in UE4.18. There are 2 problems I wonder if I can solve using materials, rather than having to go into 3DS Max to fix? Less steps in the workflow would be preferred.

  1. There are gaps between different meshes, due to the meshes in the CAD programs not being accurate. The gaps occur in all directions. Is it possible to use materials to find the nearest edge, and blend between?
    Similarily, you will see in the bottom right corner, a tiny blue line where a small hole in the mesh is shining light through. Can this be closed with the same methods?

  2. You can see the mesh in the background is quite ‘chunky’. Can this be smoothed?

Thanks.