72/144 hour transit visa for both ways (round trip) ?

I am planning to buy a round trip ticket (vacation for 2 or 3 weeks)
first, FRANCE --> Guangzhou --> KOREA (planning to stay for 3/4 days, it depends)
then KOREA --> Guangzhou --> FRANCE
1st question , It seems Guangdong province does not allow 144 hour transit visa , it it still true ?
2nd question , are we eligible to 72/144 hour transit free on both ways (one-way trip + travel back) ?
3rd question , about "Ticket to a third country with confirmed seat and date", do we need to hold the real flight ticket to the 3rd country or can we show an A4 piece of paper showing that we booked online and in advance this flight. Cause when I buy online, I just print the proof of payment but I am afraid it would not be considered as a proof.