Yes,you may purchase 5 grams a day in a coffeeshop (but if you want more you just go to the next coffeeshop and buy some more:roll.
The government allows the coffeeshops to buy and sell.
It's sort of illegal to smoke on the streets but when cops spot you they will tell you to put it out,smoke it at home or in a coffeeshop.
You may grow plants at home but no more than 5 and without all the stuff like lamps and food enhancers for the plants.