I agree that only forts should offer ZOC. I like the new movement that in neutral lands you can't gain ZOC. I mean, it is neutral land. However, I don't think you can build forts outside your cultural borders can you? I forgot, been a while. Anyways, if you can't you should be able to and then forts should offer ZOC to anyone not in open borders agreement with you.
I agree on this. I would say that they should apply the same rule they do to cities only increase it. No fort may be built with 5-6 tiles of another fort. Or make it 3-4 tiles and add a 1
maintenance charge per fort. POssibly go up to 2 at a certain limit that is based on map size.
But I like the way units can move on top of other unit tiles if you are not at war. It makes more sense to me than the previous versions of ZOC. However, ZOC should be in the game but it should take more effort (i.e: Getting Mathematics & building a fort, and garrisoning units in the fort.)