[Re: Giant Kozaky] Like "Atomic Firefly", "Foxfire", and "Poison Draw Frog", if a face-down "Giant Kozaky" is attacked and destroyed, its effect is not applied. However, if a face-down "Giant Kozaky" is attacked, and is not destroyed by the attack, if "Kozaky" is not face-up on the field, then "Giant Kozaky" is destroyed by its own effect after damage calculation, and damage is inflicted by its effect.
[Re: Giant Kozaky] If "Drillroid" attacks a face-down "Giant Kozaky" while "Kozaky" is not on the field, "Giant Kozaky" is destroyed by the effect of "Drillroid" after being flipped face-up. The effect of "Giant Kozaky" is not applied and it does not inflict damage.
[Re: Giant Kozaky] If "Giant Kozaky" is face-up on the field with "Kozaky", and "Kozaky" is equipped to "Relinquished", "Giant Kozaky" is not destroyed because a card called "Kozaky" is on the field.
[Re: Giant Kozaky] If "Giant Kozaky" is equipped to "Relinquished" as an Equip Spell Card, "Giant Kozaky" will not be destroyed by its effect because it's not a monster (even if "Kozaky" is not on the field).