I'm quite new with Ansys, so here is what i know: 

According to the video you get the pressure from the interference contact, with Normal stress on the shaft.

This is an imported 3D modell file from SolidWorks. I did not create cylindrical coordinates system.

With planes of symmetry supports you mean like boundary condition, fixed supports etc?  In that case i have no boudary conditions for that modell

The figure with width W, is for further calculations to find the Force needed to , irrelevant for pressure calculations.  Page 2 of slide Link.

Young's modulus = 200MPa  and Poisson ratio = 0.3 

For my mesh i used:

Default for whole assembly, Body sizing on 3mm for shaft (I focus only pressure that occurs on the shaft).

Inflation on shaft with 0,1 transition ration, 5 layers and 1 growth rate and Face mesh on shaft.