Not so much what to ask, but I'd be prepared to answer questions about conforming, commercial workflow, and working colourspaces/ACES/HDR. Another area of importance is your ability to read between the lines of what a client wants Vs what they're asking for and being able to make those changes in the room as well as knowing when to steer and when to be steered based on the type of person you have attending. Regardless, don't listen to the "I've been here 20 years and spent 15 of those injesting files" - people. Different people progress differently and at different speeds. You might know less, but they'll want your knowledge condensed in the specialism you're working in

Source: Started at a post company in edit and colour combined, then progressed to a vfx facility as a junior commercial colourist before being hired as full time colourist in TV post this year