Changsha > Beijing > Singapore. 1 hr 45 min transit

I'm travelling on the above routing Changsha > Beijing > Singapore with 1 hr 45 min transit time, all booked via China Air. Will time be sufficient? Will China Air interline and check the luggage all the way onto the next flight or do I need to collect it at Beijing to check again? Another thing, do we clear international immigration at ChongQing or Beijing in my case?