Hi, I'm not a medical student, I am pre med, but I did intern/shadow at Shanghai East International Medical Center for 2 1/2 months. Though the website does say things like that, they do allow 4 weeks. In general it is 2 week rotation per department, but you probably can request once you arrive depending on you.
I met a few Germans who did do 4 weeks but to truly maximize your experience it is best to do the 8 weeks. They give you a certificate in the end that has your filled out hours that you spent in the hospital.
Have fun! It is a very interesting place, different ethics and medical treatments. More than 6,000 patients are seen in that hospital so plenty of exposure to various cases.
For the English/Mandarin, English is fine, the professor or coordinator of the program usually knows English. 🙂
Plus, the older head departments love trying to speak English so they will want to practice it with you. Haha