No you won't work 6 weeks straight. The CAAC rules are mirrored after the FARs. Typically you could expect to work 4 days on and 2 days off while working to get 150 hours over 2 months so 75 hours per month. They are short on pilots and overtime is generally highly compensated. Tianjin is cold in the winter but a HUGE city with lots of interesting things to do although being able to speak Chinese will definitely improve your QOL. It is about 1 hour via train to Beijing. Air quality can be poor during the winter. Chinese flow control can be tedious and Tianjin is always a bottleneck. Overall a good job and will open doors to more jobs in China. Go For It! Good Luck!