1. To talk about Hong Kong is to talk forever! Lets just say it is a divided society at the moment, division even appearing within families. It will take some time to solve and everyone settle down.
2. The riots are unfortunate, but it is not like Hong Kong every saw it before. During the Umbrella Movement there probably was some action with the police, don't remember everything.
Here in 2016, there was a big riot in Mong Kok, over something.
Some just like to riot.
3. Here is long series about the Vietnam War with a lot of old footage.