I have spent many nights at different Chinese airports, and also abroad.  No one bothered me, just found a seat and relaxed, many others were around doing the same.

I doubt it - I was able to spend overnight at Zhengzhou airport, and I'd never even bloody well heard of Zhengzhou!

No problem, specially that You have booked another flight from there... but nobody will care about it anyway just relax, but don't sleep for obvious reasons. 

And it goes for almost any airport. 

In some european or in US some security might ask You for reason of so long stay there, but next ticket is enough to them to tell You "have a good time"

  I did 12 hours in Hong Kong airport and 24 hours in Cairo. You've got a ticket, you've got a right to be there. Make sure you've got plenty of cash for beer and a good book and your sweeeeet.

Sure why not. I recently stayed overnight at Guangzhou airport because I got in at midnight and had an early flight. I found a nice single Chinese girl that spoke English to pass the time with.

Nobody will kick you out of the airport.... and if you are at Terminal 2 then i think they even have some 24 hours restaurants where you can spend some time... If Terminal 1, then i know they have Mc Donalds which opens 24 hours.... goodluck...

i think you can if you do not afraid you will lose something.Also you can find some store like MC and KFC.which open 24 hours.

Yes, I have had to spend time there on two different occasions. The last time was around 3 months ago.