Fisher project_Basic Rig

This is my first rigging test video.
If you have any idea , please let me know. I'm all ears.

and I 'd like ask Jose Antonio Martin Martin a few questions.

1.why do we have to make a "spline orient"?
I think following the root joint is much easier to animate.
or is this a request that you often hear from the animators?

2.Do you need to create a control option for the wrist joint to to make it follow "elbow joint's rotation" or "hand ik control's rotation"?
just like this video: https://vimeo.com/388201199