ATTACK DIE VALUE

Can a unit's ranks ever count as 0 for determining attack dice?

No.

When both an effect granting a +1 rank, and a -1 rank are on the same unit, does one overrule the other, do they combine?

You determine the overall modifier, then apply that to the unit. For example a unit at max ranks with two abilities affecting it, one that has it attack at +1 rank, and one that has it attack at -1 rank, would attack at max ranks.

If a unit has an ability that looks to ranks and modifies attack die, such as Lance or Boldness and Courage’s +1 Attack Die at max rank, is that impacted by effects that say ‘-1 rank for attack die’

No. Effects that modify the attack die value of a unit only impact which number under their attack profile on the left hand side of the card you use. For instance, If a unit with Lance is under the effect of ‘-1 rank for attack die value’ but is otherwise at max ranks, they will roll the additional bonus dice. A unit with Boldness and Courage that is at max ranks, but is under the effect of ‘attacks with -1 rank, or lowest attack die value will still get the +1 bonus die.

ATTACK DIE VALUE

Can a unit's ranks ever count as 0 for determining attack dice?​

When both an effect granting a +1 rank, and a -1 rank are on the same unit, does one overrule the other, do they combine?​

If a unit has an ability that looks to ranks and modifies attack die, such as Lance or Boldness and Courage’s +1 Attack Die at max rank, is that impacted by effects that say ‘-1 rank for attack die’​

Can a unit's ranks ever count as 0 for determining attack dice?

When both an effect granting a +1 rank, and a -1 rank are on the same unit, does one overrule the other, do they combine?

If a unit has an ability that looks to ranks and modifies attack die, such as Lance or Boldness and Courage’s +1 Attack Die at max rank, is that impacted by effects that say ‘-1 rank for attack die’