--do they stem from spinal damge, from damage to nerves farther down the periphery, or both.

The problem is, the exact same neural symptoms can stem from damage to peripheral vs. spinal damage--although, technically, damage to the nerve ROOTS from spinal stenosis/arthritis is radiculopathy (from the Latin for "root"), which is simply a subcategory of peripheral neuroapthy, which, as Rose suggests, involves any sort of damage not to the brain or spinal cord proper.

You would not be the first person around here to have both spinal problems and peripheral neuropathy problems contributing to symptoms, though. There is even the "double-cursh phenomenon", in which a given nerve pathway may be impacted both at the root level and farther down the periphery, and while neither insult individually might result in symptoms, taken together enough of the signal is disrupted to cause them.

This is why the search for the causes of neural symptoms is often a long, expensive process of elimination, and may not yield definitive results--especially when it comes to EMG/nerve conduction studies, which, as Dahlek notes, may well depend on the temperature in the room (this has a marked effect on nerve conduction) as well as the electrode-placing and intepretive skills of the tester.

You mention a few terms early on. You now know about "peripheral neuropathy" versus "radiculopathy"; "axonal" refers to damage to the nerve fibers themselves--the axons--and "demyelinating" to damage or stripping of the meyling sheathing surrounding the larger sensory and all motor nerves. One can have "primarily demyelinating" damage that allows the axon to be exposed to problems, or "primarily axonal" damage that results in demyelination from the inside out. Small-fiber neuropathy--damage to fibers that subsume the sensations of pain and temeperature--is by definition axonal, as these fibers are so thin they do not have myelin coverings. You may also see terms like "mononeuropathy" vs. "polyneuropathy"--one nerve versus many.

I suspect you have effects both from the chemotherpay and your lower spine--and your chemo regimen may well have contributed to/exacerbated your lower spine deterioration.