Hello there!
I dont have much experience yet, but there are few things I thought I would share. I took my macaw (B&G) when she was 3 months old - I really wanted unweaned baby (I would take even 2 months old if that was possible at that time). Why? Well I just believe that you make a special bond between you and you macaw, not that "normal" like everybody else, but like a TRUE parront and child. Also they are too cute at that age

Well the problem comes with hand feeding and safety in general. You must be PERFECT at everything you do at that time. I think they usually wean between 4-12 months, mostly at about 5-6 months old what I read. It is just just better to let them wean when they want to, do not push them ! Some may take a long time to wean. There are 2 groups of ppl - 1 that does not approve selling unweaned chicks (because of the hazard of poor handling, safety etc.) and 2 that do this. I am glad that we got our girl unweaned, it was like the best time of my life, but I can imagine the horror if someone incopetent gets this little baby, and screws up. That ends up mostly in death of the parrot. It is very sad.
I saw several behaviour problems when handled poorly at small age - like fear of hand, water and this things. It just takes SMALL thing to scare them at this age, and it takes AGES for them to start liking it again. When a macaw is weaned too early and sold, it is possible that the macaw would start to want being hand fed again (what I know) and that is problem, big one.
At age 2 they really shouldn't be in cage yet, what I know mostly they but them in safe boxes with some towel papers or pellets under them. They eat like 3-4 times a day. They should get 10% of their weight in formula. At age of 3 months they usually start climbing around, so it is ok to be for then in cage. At that time, we fed our Ciry about 2-3 times a day, but mostly only 2. At that time, you can handle them as you want. It is just up to you what to do, the important thing is proper hand feeding.
I am very saddened when I see photos on Facebook of macaws that came from the same breeder as mine. Some of them have really poor conditions - I am talking about not a lot o toys, things to chew on and this things. Just a cage and a macaw alone in there. Well that was kind of off-topic
I know that I did not answer all of you questions, but I hope this helps you a little bit, if you have any more questions, just ask.