To answer your questions:
+ It's a singing competition for veteran singers. To show off their skills and talents.
+ It's based off the "I Am A Singer" format from Korea
+ Jessie has won every week except this week (winner's perf is under the cut)
+ China is one of the, if not the biggest, commercial markets and a place that western labels are eyeing to break. You can read more about that in this financial times article.
kz tandingan had the winning performance this week.
Tien Chong has done a couple interesting arrangements during her performances. Some better than others but she's trying!
Jessie J really toned down her Jessie-ness during that Ain't Nobody performance but Rolling in The Deep was just next level. Chose mostly power divas because I know ONTD loves a good power diva.
Source 1, 2, 3, 4, 5, 6, Financial Times