How about the trip from Hangzhou back to Shanghai? It will be on a Saturday morning. Need to pre-book?
Generally speaking, you are suggested to book the train tickets online in advance. As I know, TravelChinaGuide.com provides such service. If interested, their contact information is bookingtravelchinaguide.com.
May I know which shuttle bus to take to Lanzhou Train Station? And will it be enough time for me to catch train to Xi'an which depart at 1:40 am?