Questions about Daybreak 2 for when Horizon releases (Daybreak 2 spoilers)

With Horizon releasing in the next couple of days, I have a couple of questions about the calvard games, really db 2 that I was wondering if Horizon answers? Obviously no horizon spoilers please, but if they were answered already before horizon please let me know.

1. What was Hardwood's betrayal exactly? I'm very confused on what the oathbreaker did that labled him as a traitor. Cus Walter and golden talk about how the professor was upset that oathbreaker took his stuff and there's also him revealing the full truth about Quatre and Renne when they were in the D.G cult, but either one i wouldn't constitute as big enough to be a massive betrayal. Like is it suppose to be vague that we don't know?

2. What is the difference between what Iscariot does versus what Kevin does? I know that Iscariot and the gralsritter have different goals and work ethics, but with Kevin being the heratic hunter, I'm confused why isn't he a part of iscariot. The captain hasn't been revealed yet, but I don't believe it would be kevin, so im not sure.

3. Does the gralsritter not know of nina's true identity? I recently replayed daybreak 2 and noticed that with the celis portion of act 3, the camera purposely shows Ashladd looking at nina for a split second, obviously cus he knows who she really is, but in that entire portion, we never get a moment of that from either celis and leon, so i was wondering if they, and by extension the gralsritter don't know of her, her true identity to be clear.

If anyone can answer these, it would be greatly appreciative. Thank you