I think I gave away the answer to #1 during 0.1
The most relevant clues i have picked are:
Chapter 1: "you may even have the potential to win over the strongest Karlsson girl of all, perhaps there is even some Alexander Karlsson in you" and "Discover who you are and you will be free".
Chapter 2: "Your father. What he did to me is..." well, the complete scene.
Chapter 3: "That girl hair was like fire" and "I remember being here once when i was a child".There are closely bound together since childs. The gambit was planned since that day.
I'm convinced that the ultimate goal is aligned to the sister that i like more. Veronica, and his role as a judge and participant at the same time. And the protagonist and his role to influence and perhaps change Veronica personality for good. Alexander Karlsson ultimately wants to save his most loved and promising daughter to repeat his same error with Callista. But he need to test her, his personality and ultimately his own feelings. She once says she enjoys her life and recognice that she is evil. But Alexander was evil because he lost his true love, maybe he wants to give Veronica (or any of his daughters) the possibility to fight (even againts her other sisters) for the man she loves most. The players of the gambit are the sisters, the protagonist is just a key... a key that can change the destiny of anyone, a key to open a heart and redeem the most powerful woman from repeating Alexander's mistake.
Well, i at least hope there is that way. As i mentioned before, i deeply fall in love with Veronica and wish one of the 15 possible endings are spending my life with her.