Extra 3 will disable the takedown feature on the lightbar, Extra 5 will enable the white flashing lights to the lightbar.
Not for the vehicles in this pack. @Reed Walker has no intention of adding them for this pack at this time.
Adding some lighting features to the rear window, would increase the interest in the model in my opinion. Deck lights are a necessity! Something along the lines of this: http://ak.picdn.net/shutterstock/videos/3305813/preview/stock-footage-rear-police-car-flashing-lights-back-seat.jpg