EGR: exhaust gas recirculation. It does exactly what it says. Its to help with emissions and if its faulty it can throw a code. I mean unless its fully clogged or just venting to the atmosphere or just stuck closed or something. 

I don't know about scanning tools,  I just disconnect and plug the vacuum line to the egr valve and with the engine running, apply vacuum to the valve using a  MightyVac.  If the idle changes, the valve is working.  If not, the valve is crudded up.

Honestly, do we even need it?

Can you remove or bypass it?

If you delete your egr system, your engine will run hotter so I would suggest you get a lower temperature thermostat.