From the top of the backswing should our intention with the chest and stomach be to rotate all the way to the finish or are we supposed to rotate back to where we were at setup and the rotation to our finish is a result of our arms and club pulling us around?
If you are achieving a decent X-Factor Stretch, your hips will be rotating to ~45º open to the target while your chest/shoulders will be lagging behind to impact... and your "stomach" will be carried along with your hips because it's the "core" section of your swing. The stretch twisting occurs mostly in the thoracic spine because the lumbar spine is somewhat rigid.
It's preferable to keep the abs taut in the swing; they can be let loose but that means the side and back muscles must take up the additional stress and strain. A loose belly is the sign of a weak swing. Old pros can get away with a slack belly because they have evolved to the point of being able to compensate. If you are a beginner with a loose belly; forget it.
In correct kinetic and kinematic sequencing, the hips pull the chest/shoulders around, and the arm action follows. If you inject the arms and club prematurely into the sequencing you will upset efficient sequencing... that's obvious.