This is how I understand your question:
/work/jobs/banker
/work/jobs/police officer
/work/jobs/nurse
/education/???/undergraduate
/education/???/postgraduate
/education/???/pupil
/education/???/apprentice
/education/???/student
Q1: Why do we need the ???
category at all? Why not have:
/education/undergraduate
/education/postgraduate
/education/pupil
/education/apprentice
/education/student
Keep in mind that job
is a very generic word in English, it does not merely mean "a paid position of regular employment" (Google), it also means:
Dictionary.com: anything a person is expected or obliged to do; duty; responsibility:
Merriam-Webster: a specific duty, role, or function
Macmillan: your duty in a particular situation or organization
So the question "what is your job" can be legitimately answered with "I am a student".
However, in your specific context, I have no idea what you're trying to distinguish "student" from.