You use this card's [Opponent's Turn] effect to trash a card in your opponent's security stack. Does that card's [Security] effect activate?

Which player chooses the cards to trash from your opponent's hand with this card's [On Deletion] effect?

While this Digimon is in my battle area, my opponent's Digimon checks my security stack and flips over [BT1-107 Holy Wave]. Its [Security] effect activates, adding a card to my security stack. I ended up with the same number of cards in my security stack, but does this card's [Opponent's Turn] effect still activate?

I have 2 copies of this Digimon in my battle area when an opponent's Digimon does a security check, removing a card from my security stack. Do the [Opponent's Turn] effects on both copies activate, trashing 2 of my opponent's security cards?

If my opponent uses a card like [BT2-020 Gallantmon] to trash a card in my security directly, can I activate this card's effect?