For the cost, it is hard to say, you would better consult the railway station staff directly. And usually, waiting room is available for each train in the train station. You can find the waiting room No. on the large screen display. And the staffs at the ticket barrier generally begin checking about 30 to 45 mins before the train’s departure. Hoping this info. is useful for you.

Hello Ms Crammond, Just a tip about BJ South Station - brand new, one of the best I've ever been to. If you use the subway, it arrives directly under the station, go to either end of the concourse and make your way to the waiting rooms at the top. Once there everything is so easy to find. Have a great trip.