Basics: Draw distance/fog and lighting specific object

Almost a bit embarrassing asking this but I’m using too much time at this point.

I have a simple box mesh with the default ocean texture attached (see image). My play area is located at a high altitude and as such I can easily see where the ocean ends.

I need a guiding hand for the following:

  1. I was thinking about having the ocean gradually fade away into the background. What’s the best approach to doing this? Fog? I still want to see the sky sphere.
  2. I also want the ocean to be specially lit by a directional light but I don’t want this light to affect any other geometry/architecture in my level. How do I go about doing this?

If I’m totally off with my direction here then please let me know. I just want an ocean plane that stretches into the horizon or gracefully fades out. A simple performance-effective solution will do.