Practical Info request on luggage storage, opening hours and left luggage options

Hi, we would like to visit the Terracotta warriors on March 17th. We arrive on the train at Xi'an North at 14.11.
If we take the free shuttle at 15.00 to the Warriors will we have enough time to see the whole site?
Is is true that the site is open longer hours after March 16th? Is the last arrival time 18.35 or must we leave the site at 18.35? What time are the return buses?

Where is the best place to leave our luggage? At the Xi'an North train station or is there a left luggage site at the entrance to the Warriors?

Many thanks for your help.