This are a couple of go-to plot developments for series like these. There are no real good guys (a la Breaking Bad etc.) It's a kind of a sick trick to get people to root for essentially vile people. The next is to always take it to the extreme, and then in the next episode, prove that it can get more extreme. If you accept that as a given, it makes it easier to stay onboard.

I do give them points for the quick and concise backstories of the characters. It helps to make their actions a bit more believable, like the daughter!

The Chinese angle is a definite possibility.