I can't imagine even the Watchtower would stoop so low as to place their world headquarters in a small town like Warwick and expect to receive all city services free of charge.
I believe, in order to save on fire insurance costs, they have their own fire dept at Patterson so they may do the same at Warwick. Hopefully they won't need the Police much or the school system. They shouldn't have as much of an impact on the Warwick area proper, compared to Brooklyn where they shared the streets and sidewalks with the public. They will be on their own private compound now, rather than in the middle of a populated City. They may have wells on site for water but will need power and sewer unless they've got some kind of on site system of their own. If they need outside utilities, I imagine they'll pay the same rates for those as anyone else (maybe not). Shipping and trucking needs have gone down due to less printing and shipping of magazines and paper deliveries are likely reduced in comparison to what it was in Brooklyn. In order to get the land use permits they needed, the local Warwick government may have required them to widen their main road of usage, put in sidewalks and traffic lights to accommodate the new draw of visitors and additional trucking needs.
I imagine the Warwick Chamber of Commerce may welcome the draw of outsiders to their area, who may frequent their businesses etc. In my mind, this complex will be self supporting enough that JW visitors and residents won't go beyond the walls of their own compound for food, accommodations and the like. The Brooklyn neighborhood complained about this back when I was in Bethel. They thought the Watchtower was far to insular and put a strain on the local free public amenities without having any real beneficial impact on the local businesses.
