Should I wait to Tanggu Station to buy fast train tickets to Beijing City Center

1/ Should I book the tickets now which I am not sure time to get to Tanggu station yet?
or Should I wait to Tanggu Station to buy fast trai tickets to Beijing City Center?

2/ How much do I have to pay the cab from Tainjin port to Tanggu station? How long is the trip?
How much if I take the bus 102 to the Tanggu railway station? How long does it take? Is the bus nearby the cruise port?