Travel from Chengdu to Chongqing

Hi, I will be going to Chengdu and Chongqing in this coming May. I have understood from the previous question asked there will be a airport shutter bus NO. 300 to Chengdu railway station, is the Chengdu railway station refer to the North railway station? How long does the shutter bus take from Shuangliu Airport to the railway station? How is the daily high speed train schedule between Chengdu and Chongqing? Where to buy the ticket? How much is the train ticket. Thanks