I just realized I haven't answered all your questions. Blender does allow rigs to follow the master-slave paradigm of rigging too, so you can have deformation bones constrained by the control bones, etc. It certainly isn't nonsensical - extra weight painting should be avoided when rigs get revised!

Looks like a bug to me. Maybe a dev can confirm.

Oooh I see Easing isn't deforming the mesh, unlike the other settings.

It looks like the easing property is working to me. What aspect of easing isn't working?

Glad you figured it out. I was about to suggest doing a fresh mirror modifier, you beat me to it.

Hmm weird, not sure why your having no luck on the mirror. I would retry the mirror tool after taking the poly count down. The mirror tool doesn't handle a high polys well. Also, did you have those mirror options unchecked? I mean try checking them.

If that's the case, try making the bone for the bone cylinder to TrackTo instead.

Is the geometry the TrackTo bone is constrained to also a child of the armature? Even though your idea makes sense, Blender might look at that as a circular dependency. ie) Armature [object level] -> Geometry [what the trackto bone is aimed at] -> Armature (trackto bone)

I'm terribly sorry for not responding until now -- I got busy and this totally slipped my mind! Has the issue since been solved?

Without a .blend, I can only guess how this could work as an armature-based rig. If possible, could you post a .blend to blend-exchange.giantcowfilms.com? That's considered standard practice here on Blender SE.