Hi
first go through the schematic first and then study software.in interview asking about your project and what are package are used in your board and study the footprint padstack, transmission line basic
Ask about packages, constraints and techniques requires in placing and routing high speed signal,,,, one thing that I was asked all the time is about differential signaling and its technique... surely you can irritate the person with this ;-)
you can aske him about DFA and 3D modling of the PCB to easy check spacing in the case,Signal intergrity,if he know the PCB fabrication process to be able to comunicate with your Fabrecator. ets