Pudong Airport to Changshu - fastest/easiest way?

My son arrives at 4:20 on Jan 4 at Pudong Airport. What is the fastest/easiest way for him to get from Pudong to Changshu? If it is the shuttle bus 5 from Airport to Shanghai Railway Station then the train, is it easy for him to buy tickets on the train when he is there? He has a US passport but a Chinese resident visa but his Mandarin is still very rudimentary.

Thank you.