For a "Mountain fold," ford the paper away from you, so that the fold is closer to you. For a "Valley fold," ford the paper towards you, so that the fold is farther from you.
This is another Bringhurst special. The wings flap only under certain conditions. I'm not sure what they are. Both wing folds are necessary. The nose points backwards
Hold the plane by the body, push forward, release, and pray.
If the plane doesn't seem to be flying, try sharpening your creases.