Sorry I haven't posted here in a while, been working on the lua code for the wonders.
As of right now this is what I have done:
Hoover Dam
Now gives +5

in the city it was built in, and supplies +10

to all other cities that are connected AS LONG AS they are within 15 or less tiles of the city with the Hoover Dam. This "production bonus aura" is limited to 15 tiles, but it doesn't matter if any of the cities are on an island or the same continent, they all get it. If one of your cities with the Hoover Dam's "power connection" gets captured, the enemy Civ doesn't get the bonus. They would have to take the city with the wonder to get anything.
As for the picture, I am going to stick with TPangolin's version. Thank you for your work WileyNg, I think I just like the richer colors in his version. But! If you want to polish the others, I would like to see them.
Potala Palace
Gives +2

+4

and provides a free prophet each time you enter a new era, so a total of 4 if you were to complete it before entering the Industrial era.
If your city were to get captured the enemy Civ would also get the free prophets when they enter a new era, even if they are waaaaay far behind in eras.
Requires you to have a religion and the city must be within 2 tiles of a mountain.
Fort Knox
So it seems the latest version of CPP does allow us to make buildings that can block gold theft from enemy spies. I want to keep that in. I also want to keep it as another fort/military base. So +10 city def and +25 HP.
But it seems we are a little over the place on what else it would do. Any other thoughts?