Here are the answers from the author Simon MacDowall:
(1) If a unit has to evade a charge, it has to move directly away from the enemy charging it (p. 39). Is the evading unit permitted to move through a friendly unit that is behind it using the passage of lines rule (p. 33)?
Yes it is allowed to pass through a friendly unit using the passage of lines rule
(2) If a unit has to retire, it must make a full retire move directly away from the enemy (p. 45). The rule says that if the unit is unable to retire due to troops in its way, it remains in place and receives 1 DP. It appears by that statement that the retiring unit cannot move through a unit behind it using passage of lines, is that correct?
No. If it passes through friendly troops it is not prevented from retiring. However enemy troops would prevent retiring. Also you are never forced to conduct a passage of lines so if you cannot move around an intervening unit and do not wish to risk DPs in a certain situation you could halt the retirees and take the penalty.
(3) Retiring units break if caught by their pursuers. However, I take it that if the retiring unit does not move at all due to impassable terrain or friendly troops, it does not break. Is that correct?
Correct
(4) Finally, does a retiring unit remain in place if it can move part of its move backward, but not its full move due to friendly troops behind it?
Yes
