Does Added Vertices created with Merge Vertices command take tile texture used for optimized object? Are these vertices are part of object optimized?

I know well how that tool works but I hope I correctly understood the question. Merge Vertices does insert additional triangles - it cures holes. There are two way how holes can be stitched:
1) without re-arranging original vertices (the default mode of Merge Vertices) - it is just like puting connectivity stitches across the hole
2) by welding vertices across the hole (called Add Points) - the nearest vertices across the hole move towards each other and collapse.

The texture (UV) coordinates for the new surface are extrapolated from the initial coordinates. The new surface will be textured. It should work for tiled textures.