short visit to Terracotta Army

We booked all our tickets here. The service is very good. Now I have another question....
We arrive in Xian by train at a quarter past one p.m. (1:15)
and our flight leaves at 20 minutes past dix (6:20) p.m.
So we have more or less 4 hours.
How long does it take from station Xian to Terrakotta Armee?
How long does it take to go to the airport to take our flight to Guilin?
Do you know if there is enough time to do a short visit to the terrakotta armee?
I saw that there is no metro line to the terrakotta armee. How much would it be by taxi for each way?