What do they call the guy/gal who is at the bottom of their graduating medical school class?

Doctor.

What do they call the guy/gal who is at the bottom of their graduating new hire class?

First Officer. Where ever the hell they want you to be!

I had a hard time explaining to my then girlfriend that I had to start all of my trips in a base where they tell me. Said base could be changed later, but for then I was stuck. She thought I could just go to BDL and "start" flying.