I've seen several such mods that do similar things already, like Warm Ashes and the miscellanious city quests from QP1 (both fantastic mods). I've tried opening up the quest .txt files from those mods to see how they're made, but I'm so new to this that I can't really figure it out.

Any advice? Ideally I'd like to have the game pick randomly from a pool of possible messages so I can just keep adding in new ones whenever.