Nowadays, finding MJ in the apartment is like finding Wild Rice. I don’t stow it, but many do for various and sundry purposes. We are in the middle of a time where many don’t know if possession is or is not legal. You can still get in big trouble if you guess wrong. Maybe alcohol prohibition was like this the first 15 years after it officially ended.
Yes. I believe in MA it is legal to buy it, but it is illegal to sell it. I'm not sure how that works.
The wise people of MA voted in 2016 to legalize recreational marijuana, but the legislature has been dragging its feet and putting up roadblocks, so on the one hand it's legal to have it, but it is also not OK to provide it to people.
I stay away from the whole thing because it just seems easy to guess wrong, as you say.