I have a 16 year old greenwing that is my constant companion...
I'll give you my version of Greenwing Macaw 101, take it for what it is worth:
The big thing about greenwings is socialization from an early age... Do that and they will go to anyone. Don't do that, and you will be the only person who can handle your bird.
Macaws are pair bond birds. In the wild they pair up. If allowed to pair up in captivity, you can get "bird mate" issues. You want to be the parent bird, the teacher, and the protector, the DAD, NOT the bird mate. The significant other in your life will appreciate not being treated like "the other woman" by a bird.
Greenwings can have dominance issues, especially the males, the way you stop that is to stop it. The bird is not in charge. You have to be big bird.
You can accidentally train a bird to bite, and to scream. DON'T!
You are taking on a bird that, if he ever used his full bite pressure, could easily bite through a human arm... (not to worry though, they rarely use their full bite pressure.) The important thing is to sit down with the bird on your lap and teach them, at an early age, not to use bite pressure on people, and not to use his beak to communicate. You do this by simple beak play games.
ALL macaws, even the tame friendly ones, will test... The lunge thing is actually a test, and a form of play... if you don't jump, and if you take it as a sign of playtime, it becomes exactly that. If the bird does the lunge bluff thing, and you start flinching... or if you accidentally teach the bird that you are afraid of it, and THE BIRD CAN GET IT'S WAY BY BITING YOU... you are setting yourself up for what is called the terrible twos... [which are often actually just the period where you have to correct your training mistakes.]
You raise a macaw the same way you raise a human toddler. With boundary setting, nurturing guidance, and lots of love and attention. Do that, and you will have a lifelong companion, and you will discover that these birds are amazingly playful, and have the capacity to love that is astounding...
I say it all the time. "How is it possible to love a damned bird this much?"
THAT is what it is like to live with a properly trained greening!
As a cautionary tale: I also did rescue and rehab...
More than once I have seen a dominant male greenwing take over a house, scream and bite to get it's way, and then end up miserable, and locked in a cage, unloved, and unable to be handled...
Then they called me to "get this thing" out of their house. "What were we thinking?!"
DON'T BE THAT GUY!!!
DO THE WORK... IT'S SOOOOO WORTH IT IN THE END!
I don't want to overwhelm you with this, it is amazing. But there is work involved.