In Gloomhaven: Jaws of the Lion, when you discard a card to negate damage from a lethal attack, do the stun or poison effects attached to the attack still apply?

Last night, four of us played through Scenario 4 of Jaws of the Lion for the first time. The Red Guard was low on health, with only 2 HP left, when a Zealot drew a critical hit +3 and added Stun and Curse, dealing a lethal 7 damage outright. The Red Guard immediately chose to discard a card from their hand (placing it in the lost pile) to negate this lethal damage. I want to confirm two specific details: 1. Does discarding a card to negate damage reduce all 7 damage from this attack to zero, or does it only reduce part of it? 2. Although the damage is negated to 0 by the card, do the Stun and shuffle-a-curse-card effects on the attack card still need to be resolved on the Red Guard?