Hiya, I am on my way to bed and can't promise I will have enough time to properly answer tomorrow, but here I might have touched on few parts of your question, albeit not all of them for sure. Also, recently I wrote a bit about the ways opium was legally dealt with in Britain (and how long it took to get there). Hope it helps a tiny bit!

Could you be more specific to what you mean in regards to "so destructive on the chinese"?

Edit: I ask because there was a lot going on with China during that time (the Opium Wars era). The government was falling apart, local sovereignty was being subverted by foreign powers, there were numerous rebellions and disasters (Taiping, Miao, Panthay, Nian, and Dungan rebellions/revolts, massive famines in the 1850s and 1870s) all within the 1850-1870 time frame. Then the Boxer Rebellion and the Xinhai Revolution in the early 20th century ushering in a period of nearly three decades of effective civil warfare.

Is there an attempt to lay any of that at the feet of drug abuse or not? Given all that was going on in China in that period it would be nice to have a boundary on what the expected destructive impact exactly was.