What does "drag" mean in the final outcome? Does friction only affect collision or is that also modeling air friction? If it's the former and not the latter then I would expect a moving object (a flag, let's say) would not be distorted by movement, only whatever inertia the mass lets it have, but if friction creates a sense of drag then the moving flag would constantly flap even after inertia bled off. Or, am I off-base and friction only affects whether the flag would flow over a hand like water, or flow over a hand like a piece of cloth being lightly tugged by the friction of the object touching it?
I would sure like some more elaboration on "Changing [mass] will affect movement." In what way? What's the center of mass do, and the inertia tensor? What is the orientation of each axis when looking at an object, and if it can't be obvious (for instance, an earring) how can you determine that? How much mass is "lots" or is there some sort of way to tell how a change to mass will affect an object? Is mass all relative, or does a 10-ton dress basically not move when the wearer does?
In terms of HDT, friction only refers to how one collision object interacts with another.
The HDT physics world (in this case) doesn't have 'air'.
Changing mass will effect movement in that, virtually all physics equations require a mass.
Depending on the calculations, and the the constraint limits as well as other factors, the difference might be a lot or not.
It's required for this value to be greater than 0 if you want to see any movement though (otherwise you would the physics calculations and end up with a static object)
Inertia tensors do exactly as what they state, the y control the inertia amounts in the various directions, I feel like I posted a wiki link explaining how it works.
I found out that trying to figure out the orientation of each axis manually in JFF is impossible. As the xml's do not store bone pivots.
All I can say is, you'd need to load up the mesh in 3dsMax or Blender, select the bone, and see which way the pivot point is facing.
Mass is relative to all the other constraints and limits.