Your UV map could probably be done better with overlapping shells to provide more pixel information to the mesh. Remember overlapping shells need to be offset out of the 0-1 region.
Anyway, from what I can see you haven't smoothed the normals on your low poly there, in maya under the polygon menu's there is one called normals, at the end of that menu is soften edge. If you are getting faceting on the normal bake make sure the high poly has enough divisions to be smooth, If you bake while the object is in smooth preview (pressing 3 on a mesh) then it will ignore the smooth preview, you can convert the mesh to the smooth preview by clicking modify>convert>smooth mesh preview to polygons.
If your not getting flat area's where you want them you can tweak the vertex normals for the low polygons faces to point in the correct direction.