While they're definitely advantageous to learn and will help you on your chosen path, I would say simply a working knowledge of them is all you NEED; a familiarity with modeling will prove useful when designing levels, while a familiarity with coding will help you understand scripting better.
The general idea, however, is that you understand both well enough to know (and appreciate) what other members of the development team are doing, and have some level of working vocabulary with them. So you don't go and say something stupid like "
We need to tighten up the graphics on level 3".