Make sure your model is not underconstrained. If you only have a constraint in the radial direction, you would also have to constrain rotations (theta) as well as z.
I had a contact problem where the model was underconstrained but still solved. The results showed one of the parts "growing"...
It should be 1 (no reduction) unless you have a good reason to change it. This factor modifies the elastic portion of the strain life curve. (It's also used to modify S-n curves, but that's not applicable to Mechanica.) Sometimes people use it as a correction factor to account for welds. The...