We were all fresh graduates at some point. Your summary of the design office, nearly correct, these days you only tend to get to work on one part of a complete aircraft (ie; the wings for example ) as most projects are joint european cooperations, hence we only get to do bits of aircraft.
At a small compnay then everything and anything will go on in the design office, at a larger institution you will have departments dedicated to a particular tasks (hence no defined deisgn office but a multitude of departments contributing to the design task).
I envy the people whom were in the industry in the 50s and 60s so many whole aircraft projects going on.
Anyway good luck