Help with ZOC-and side note.

[Dragoon!]

I'm having a bit of trouble understanding ZOC-In the current versions, you can still move stacks into the 'red zone' and, although you get a message that your movement was blocked in the countryside, you can still complete the move...This is in both AACW and NCP.
Now..As I remember it, in an AACW game I was playing with an earlier version,
you couldn't drop a stack in a 'red zone' region, or plot a move through one..You weren't allowed. Am I remembering this right?
So..what's the story? Is this just for retreat, or a bug? or, is it a 'roll' to block movement? the manual seems to indicate that you shouldn't be able to move through the 'red zone'.
* the bull run scenario in AACW is a good place to see this..You'll pretty much start with a ZOC restriction, and you can move out of it.

As a side note..What's the difference between passive posture and defensive with retreat ROE? still get the penalty if attacked?