The front cloth is made of about 10 parts, but you can notice the shading where each part bends, around the X axis?

In an effort to correct this shading, I've made sure Smooth Polygons is checked On, in my Render Settings; and have increased the Crease Angle, of each part, from 80 all the way to 500!  But the Shadows, where the xRotate bends happen, did'nt change at all?

A crease angle of more than 180 is useless, 180 degrees is the most extreme angle two polygons can have with each other.

I see what you mean about the shadows. There's two things you can do: 

1. adjust the shadow settings. Maybe the shadow min bias is too small.
2. convert the loincloth to dynamic or hybrid cloth. The front part will be one unified mesh and you'll get rid of the ridges.

Here's how you convert to hybrid cloth:
a) Load the .obj file associated with the loincloth figure into Poser using File->Import->Wavefront .OBJ
b) Use the grouping tool to separate the cloth into 3 parts: hip (keep this name!), front and back. 
The hip group will already be present, leave it as it is. Assign all polygons of the front flap to the new 'front' group (using 'add group' and choosing the front01, front02 groups etc will be the easiest way), and assign all polygons of the back flap to the new 'back' group. 
Delete all other groups.
c) Export this prop as Wavefront .OBJ, check "Keep existing polygon groups" and "Weld identical vertices"
d) Reimport the prop, remove the old one.
e) Switch to the Setup room. Poser asks if you want to turn the prop into a figure, confirm this.
f) Apply the loincloth figure from your figure library to the prop.
g) Rename the front01 bone to internal name 'front' (case sensitive) and the back01 bone to 'back'
h) Delete the front02 - frontXX bones and the back02-backXX bones

i) Switch back to the Pose room. If you've done everything right, you'll have a loincloth figure with three body parts: hip, front and back. If you've forgotten or mistyped something, Poser will warn you about polygons not being assigned to a bone. In that case, stay in the Setup room, inspect the names (the group names MUST match the bone internal names EXACTLY. Case sensitive!) and the groups, and fix the errors.

j) Save your new figure to the Figure library.

To turn this figure into a hybrid cloth:
a) Load and conform the new loincloth figure;
b) Pose your angel figure
c) Select the loincloth figure and go to the Cloth room
d) Create a new simulation. Set the number of drape frames to 10 or thereabouts (no less than 10)
e) "Clothify" the front body part of the loincloth. Let it collide against the angel figure (only hip, buttocks, thighs and shins, maybe abdomen, no more. Set the collision offset and collision depth to a low value, e.g. 0.2 Check "Drape from zero pose"
f)  Repeat step e) for the back body part of the loincloth.
g) Calculate the sim.