There are dual dialogue which can give traits (ie after reading the diary on the body on the starting beach, or at the tutorial cave entrance), which can provide
various bonuses. Other dual dialogues are tracked to determine the main characters' overall affinity (how much they agree) and attraction (how much they like each other), which influences a very small part of the epilogue.
You can ask anything game related in your own topic. Anyone reading through would see the progression and stop reading if they didn't want spoilers. You can always start general and become more specific (after you get to Luculla Forest, if you head east...) so people are warned if they have not gotten there yet, or you can use spoiler tags by enclosing text in [ spoiler] and [ /spoiler] (with spaces added, so they stay in plain text).