I like some of those, particularly the last one--I've seen something similar, which was "what could you talk about for hours?"
I'm reluctant to ask "most," "least," or "favorite" questions, because almost nobody has good prepared answers, except to the trivial ones like "favorite color." Which is not an effective question for getting insight into someone's worldview.
I like asking people what their favorite playing card is, and acting confused if they don't have one (but about half the time they either already had one or are willing to make one up to play along).
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