Hi Michael,

> what happens in NX if you hide just some of the faces?
> Do some of the edges change color but not all of them?

That's one thing with NX, once an object is a solid or joined surfaces you can't hide individual faces, NX considers the object as one entity.
There is away around this so I can answer your question.
The edges display the same as the gif I posted previously.

> What happens in NX if you have some faces colored differently
> than others, what does it do for the wire colors in that case?

You have to remember that the colours in NX are not associated with layers, they are a separate thing altogether.
You might find this a bit unorthodox or strange.
When you create a cube in NX the colour of the solid is what has been set as default, let's say Red.
To change the colour you select the cube and change it to green then, shaded=green with black edges, wireframe=green edges.
If I change one face to blue then, shaded=green and blue with black edges, wireframe is still green.
If I select all faces not the solid (this is a filtered state of selection) and change all the faces to blue then, shaded=blue with black edges, wireframe=green.
I hope your following this :S
So applying a different colour to a face is like having a ruby and painting the facets yellow, the underlying ruby is still red.
The same goes with a separate surface, you can choose to change the colour of the surface or change the colour of the surface face, believe or not there is a difference.

You even have the option to do all the above and have any colour for edges in the shaded state as well, you could get hung up in all this and not get your job finished :)

This all comes under the Visualisation window.

Cheers
~Danny~