what is the best time to take a train from Beijing to Datong and back to Beijing.

Actually I would like to go on 25th April 2015 afternoon or mid nite and leaving DT on 27th April 2015 noon coz our flight back to Kuala Lumpur is at the mid night. I would like to skip the accommodation for a night in DT (like to stay in the train overnite) but how is the train condition? Is it confortable? Also Can we manage to visit Yungang Grottoes, Hanging Temple and a scenery place where we can see large piece of land fill with green grass and sheeps in a day ie on 26th April 2015? Do u offer these kind of tour and how much? how much is your tour package.
We have 8 ppls all adults and we r going to book our own hotel for 26th of April.

Thank you very much .