To answer your second question, here is a relevant discussion about Modal analysis. One of my replies in that discussion describes the two scale factors that can be chosen for the displacement results. Knowing that the displacement values are arbitrary, you can set the display scale factor to any value that makes it easy to see the motion of the body.

If you are not in Modal, but in Harmonic Response, then the displacements are real, and you can set the display scale factor to any value that makes it easy to see the motion of the body. Note that Harmonic Response is a linear analysis, so it includes the small deflection and small rotation assumption. That means if you make the load 10 times larger, the displacement will go in a straight line along the same direction it went at a 1 times load. At some point, this produces unrealistic deformation because the small deflection assumption is no longer valid.

If edges or faces are moving apart that should be bonded together, that means the contact is not working and you need to increase the Pinball radius to get it to create the bonds. I prefer to use Formulation MPC so I can see the Connection elements in red after the solver has run. If possible, use Shared Topology in SpaceClaim or DesignModeler to connect adjacent edges/faces, then you don't need contact.