- The textures scale is not affected by a shader, at least not if it's not intended.
- Yes, you have to create a new material for every texture, but you can use the same effect in all materials, so the coding/writing effort is minimal.
- That depens on the shader and is not a problem of the level-textures.
- You can add lightmaps to your shaders aswell, and the 8 dynamic-light-limit is there, even if you don't use shaders.