A couple of basic questions about hexsides

[Xerxes77]

I was playing around with The Final Struggle, trying to familiarize myself with the Nap system, and a couple of questions came up...

a) Opportunity fire:
In the following screenshot from Plancenoit, my Prussian unit has just moved south of the French and was met with defensive fire. The Prussians ended behind a hedge+embankment hexside, and yet the modifier for the firing French unit shows as 0%:


Now is the active turn of the French, and they fire again on the Prussians. This time the modifier seems to be applied correctly (10% from the Hedge + 10% from the Embankment = 20%):


I have perused the manual but couldn't find an explanation of why the first reaction fire had no modifiers?
I also noticed that when the opportunity fire is triggered by firing, not movement, it does show the correct modifiers, so maybe this only happens when a unit is moving?

Maybe I'm just misunderstanding the following rule: "Target units which have not moved during their turn get a defensive benefit from certain hexsides"? I took "during their turn" to mean their previous active turn, but maybe it actually means the current turn, and the hexside benefit is forfeited only when coming under defensive fire?

b) My next question concerns embankments. Their movement cost is set in the Parameter Data as 2 points. However, that seems to be the cost of crossing an embankment in one direction: they just cost 1 point to cross the other way! Again I could find no reference to this in the manual.

I'm a bit puzzled by the purpose of embankments in general. They almost always appear following elevation contours, so I initially thought of them as "ramps" of compacted soil...  however their movement cost is added to that of climbing the elevation, so they actually *hinder* movement. They also provide some protection to units stationed just below an elevation, which seems weird?

Rarely, embankments appear between hexes at the same level... I guess they essentially act as breastworks? Thanks for any insights...!