There's a fine line between remaining incorporeal and becoming too physical. My body needs to accept something is there to be used, but not so much that it becomes a burden. Too little in the way of control in either direction results in angels like Remiel.

[Kratos is still acutely aware of Raine's hand, and it takes some effort to withhold the twitches and the urge to pull away. He'd promised to bear this, and if it kept her from asking too many personal questions, it was worth the mild discomfort. Still, some of the tension leaves his back when Raine finally pulls away.]

That depends on the mode. There are two -- banked and active. They are still able to be used in both modes, but the former is less destructive and requires less space; that is the state Colette's wings are in.