When it comes to interviewing and the recruiting stage of onboarding, it's useful to separate buying and selling.(1)
If interviewing: Sell First. Then Buy.
You cannot turn down a job offer that you have not received. Thus, in the early stages of interviewing, stay focused on getting a job offer. EVERYTHING is part of the interview. Everything you do and say before, during and after the formal interview. This includes your questions. They should be designed to reinforce your strengths, not jump-start due diligence. Save due diligence for the time between an offer and acceptance.
If recruiting: Pre-sell while you're buying. Then sell.
While candidates have the relative luxury of completely separating their selling and buying, those on the recruiting side can't do that. They must be pre-selling even while they are interviewing. They want everyone to walk away with a favorable impression of the company. Even so, as soon as the decision to hire someone has been made, the organization should switch into make the strategic sale required to convert the offer into an acceptance as appropriate.
(1) There's much more on this in "The New Leader's 100-Day Action Plan" and "Onboarding"
George Bradt
PrimeGenesis Executive Onboarding and Transition Acceleration