Idk. Special places seems dumb...you should be able to smoke. In my country they will not legalise anytime soon but i am verry pleased that other countrys have an opened mind.
From personal example i can say that i have passed half of my life on drugs, not just weed. Now i know my substance and i am much more aware. Besides that i live a very productive and fullfilling life. Everybody should be free to make their own decission but also everybody should be informed. Young minds are easy and proned to derail. So yeah, 18 or over...even if this does nothing.
Driving might be an issue. Usually you are aware but some people can get very wasted and sick. So if u are driving and a friend lights up some rlly strong sht, you might not even notice that you cant drive anymore until to late.

My conclusion is to be responsable and everybody should make their decissions, good or bad.

Health care...fuck healthcare. At least that is what the govt ows you, after all the bullshit they do.