I think it reasonable to assume that in some point in time MC will confront this leader. Flashbacks are priming us to this idea. I hope it doesn't happen to fast though. I want to experiment with powers and just have some fun with them.
Regarding harem, Devs mentioned that they plan to mix and match girls, but nothing is set in stone just yet. For me it means that we need to wait at least two updates( just my assumption with no proof). Also there was some time ago teaser of Stacy with her mom so fingers crossed