Actually, Aida's mission is to keep S.H.I.E.L.D. agents safe. Looks to me like she's trying to keep them safe by putting them all in the fridge and replacing them with the LMDs. Without their permission, of course.
Maybe because the Darkhold is, basically, just an instruction manual? You need a machine to open the portal.
Probably when he became "the hero" during Helmut Zemo's bombing of the Vienna International Centre. I think he took credit for someone else's heroic act.
You are assuming the Darkhold is some kind of a self-aware evil being. As far as we know, it isn't.