An independent ticket purchase

Hi

I come with my family to Beijing in early October, I ask whether I can buy myself a train ticket at the airport terminal G 2 as soon as I came to China
We will visit the city a week and I want to buy your tickets in advance at no extra cost
So buy directly from the station there is no need to pay an additional fee?
The hotel that I would be found near the train station BEIJING RAILWAY STATION Can I buy there?

Thank you
Rami