Alas the old Greg cells are failing me again.... You are correct in the 3 mu. I was thinking of the foot troops, not the mounted. Either way it could still get messy for the poor cav, who will stand and take shooting for another turn.
But at least they can't be broken at this range.
I believe that some players (maybe including the author?) may mark the effected unit, but hold off taking the CMT to advance until their movement phase (deciding then if they want to advance and taking the test at that time if so), however I don't believe this is correct.
I usually place a white dice the the '1' facing up to denote a unit that must test to advance. Steve has special 'Halt' markers.
(1) above: The Action Sequence rules on page 24 state that you apply the results immediately. A 'CMT to advance' is a result (it is listed as a result of firing in the table on page 54). Immediately means, well, immediately and not at some later point in time.
Applying results immediately means that
1) A unit that drops cohesion does so immediately.
2) A unit that retires does so immediately.
3)A unit that takes 1 or 2 hits during the firing phase effectively gets a "CMT to advance" affect (marker) immediately, which it obeys for the duration of the turm.
There is a problem with the Reuslt of Firing table which I will correct with the next errata.
3 hits: currently states - "Retire to 3MU if closer or are wavering, otherwise may not advance."
this should read: - "Retire to 3MU if closer or are wavering. May not advance."
i.e. The current entry gives the impression that a unit that retired to 3MU disordered could still advance - wheas no unit getting 3 hits can advance this turn.
I think I've previously given the impression that any unit retiring to 3MU can still advance with a CMT. This is only true if the unit that retired was CAVALRY that took 1 or 2 hits.