That's a good question... I think they potentially would take teh same amount of dmg BUT your attackign unit would not really take any dmg because the unit is facing the wrong direction.  However, I think we would REALLY need to slow down the "turn" speed or something... and that could throw other things out of walk.   But I do like the strategic/historical aspect about trying to ambush, out flank etc.

Pathing clearance is determined in the UnitMotion component, I believe, with PassabilityClass. There are a couple of standard sizes. The bigger the passability class the more problematic the pathing performance. 

It would be so cool if the Minoan priestess could wave snakes around. 

Maybe both, but the Tachara is the Achaemenids' major "fancy" special building.

Would it be too hard to make it so if units get hit from the back it does more damage? I am thinking for strategy purposes, then there would be an advantage to attacking from behind