RSM, I'm happy to see your reply! I wish more people would come back and see whether they got anything out of what someone said. Not just to be "nice" and "say thank you," but to see if they got what they needed, ie, did the problem get identified. CS is obviously about being able good interpersonal skills, but my view of it from my own world has been that it doesn't do any good to be "friendly and courteous" for long if you don't know how to find a problem and remove it, then prevent it, because you learned how to spot it. So it feels good to me to see you coming back and looking for more.
Icebreakers...you want to create a situation in which somebody is less stressed and can communicate "naturally." Ask them if they drove (what did you think about the traffic); if they say taxi cab or transit or whatever else, was the driver chatty, was your father/friend/car pooler on his way somewhere, did you see the construction on highway X or were you not coming that way.....
If you have a few hallways to navigate through, you can joke that you will eventually get to a place where you can talk (I have used the word "labyrinth" before, and it is well-received). I have gone through life noticing that others notice I am a fast walker, and I have turned back and made jokes about that very human thing as an ice-breaker.
When you're in the midst of the interview and trying to get a good sense of how this person has applied or would apply their skills in a tough situation....You can turn some of those "formulaic" behavior-based questions into a more down-to-earth conversation. For instance, I remember when I first started interviewing, I would try to take a prescriptive list of questions and inject some personality into it to make it less dry and threatening (or EXPECTED) for the other person. That soon evolved into me translating the questions. One of the favorites has to be "describe a situation in which you confronted a difficult customer and how you handled it" or " What areas do you need to improve upon?" Well, I would say instead: "I'm guessing, you tell me what you think, that you must have found X to be hectic or something that came up on you all of a sudden, did you manage to come out of that OK, etc" and "OK, we've been talking about how you did X, Y at this place, that place, is there something you would have wanted to get better at, either because you didn't have the opportunity, didn't know how at the time...or Is there something you have been wanting to explore and say you got there, but didn't know how to do it?"
Those phrases might be less intimidating and less "sanitized," as in scary dentist's office, but I think it would be important to make sure that the answers (skills, learnings from experience) come out with that more relaxed approach and phrasing. If they are not providing self-critical responses (ie taking advantage), then you can find a question that is less down-to-earth than my phraseology, and they could perform for you on the plus or minus side.
It's hard to spell it out for me, and it's not so much a "formula," but an attempt at a formula is to say that you want to create a situation where a human being in a human challenge is reasonably comfortable enough to show what they have got to offer as a performer and see if they will make use of the relaxed rapport wisely. I can tell you that probably the majority of times I needed to interview someone, I needed to be called by reception or paged, because I was on the heels of a meeting or some business activity. It's an uprooting feeling, and I need to quickly compartmentalize and make this about time for someone who needs to see a representative of what the company has to offer and with the body language and "personal" speech to express it. I can't do that by conforming to an official sheet of questions beneath which I would jot down the person's answers as they watch me (terrified) , but I can get at some results by making it a "conversation" to learn from for me as a human hiring manager.
Did I get closer to giving you what you needed?