Neuropathology is a sub-specialty within Pathology -- in order to be board certified by the ABP you need a primary board certification. This can be AP, AP/CP or CP (the latter being theoretical). Neuropathology training programs are two years long, and can be paired with 2 years of AP training (the so-called 2+2 route) or can follow full training in pathology (3 years of AP, 4 years of AP/CP). There are also paths to NP certification for individuals with board certification in Neurology (or Neurosurgery or Psychiatry): 2 years of NP plus 1 year of AP.
There are a few training programs with AP and NP tracks which commit to individuals at the time of the match to provide them with the AP/NP 2+2 path. This is not part of the match (there is not a match for fellowship positions) and happens for clearly committed individuals. As you would expect, these programs are primarily at large academic medical centers with strong programs in both AP and NP.
Neuropathologists are usually responsible for both autopsy neuropathology and surgical neuropathology. The surgical material usually includes all specimens from neurosurgeons, as well as nerve and muscle biopsies. CSF cytologies are done by neuropath at some institutions and by cytopath at others. Sometimes ophthalmic specimens are shared between the neuropath and dermpath services (depending on the type of specimen).
In terms of careers, the most common paths taken by neuropathologists are:
1. Academic institutions, often with a significant research and/or teaching component
2. Large hospitals or practice groups with active neurosurgery groups (these are sometimes found away from academic settings).
3. Practice groups in which there is a moderate volume of neuropathologic material but where the neuropathologist also signs out other material.
4. Forensic settings (NP/FP training) with many larger ME offices having a designated forensic neuropathologist.
Many people following the AP/NP 2+2 track come to the discipline with a research background in neuroscience. They know that they are interested in neurologic diseases, that they like neuroanatomy (required for much of the work) and that this is where they want to focus. This isn't a field that people choose because it is the path to riches and power but rather because it makes them happy and satisfied.
If you think that you are interested in the field, you should find the neuropathologist at your medical school and spend time with her.