Hey Ryujisama, Welcome first off. Second, I would spend some more time defining the head. You've got quite a bit of poly's that are doing very little as far as defining the shape. Try focusing on the main planes of the skull and eliminate smaller faces that don't help to define the silhouette. Also included in that would…
that depends whether it looks how you want it to look. face-weighted normals isn't some defined method of building things - it just means that vertex normal direction is affected by the relative size (area) of the faces it's attached to and generally means you get nicer shading without manual intervention.