Interview questions weren’t unusual, and there’s some time built in to the day for touring and socializing, or at least that was the way it was a couple years ago. It probably goes without saying you want to be friendly and pleasant to the other candidates. You obviously won’t be expected to be conversant with every professor’s work, so if your interest is neuropsych, focus your interview prep in that direction.
BTW, the faculty are very accessible and collegial (worked as RA there before applying but wound up accepting an offer from another program). Housing near UTSW is relatively reasonable; if you decide to go and are unfamiliar with Dallas, PM me for suggestions on areas to look at/avoid.