Either a dress or slacks would be ok for the dinner (whatever you'd be comfortable wearing to a nice restaurant). I would NOT go above the knee on your suit. I did see one or two interviewees who wore skirts AT the knee, but none who went above. Most chose below the knee or went long (above the ankle). If I were you though, I'd keep looking for a pants suit, you'll be more comfortable...and warmer. Remember, most of your interviews will be during winter.