Welcome to the forum! You have come to the right place to ask questions, we have many members with years of experience here. I love how you are asking questions prior to getting a parrot. Here is a link with some things to think about:
What students should ask before getting a bird
I disagree with some of the info you have been told, and would like to give my perspective.
I don't agree with multiple things in the copy and pasted section from Bird Eden.
I find that baby birds birds less when they are young. With my conures, the biting gets worse once hormones kick in, and will often happen each they are hormonal. My GCC bites even when he isn't hormonal.
Some birds will do tricks, and some won't. To say that all GCCs will do tricks is to set someone up for disappointment.
I take issue with "once in a while'. Birds need to be let out of their cage every day, for as many hours as you can.
As far as the diet of veggies listed, we have a much better list here:
https://www.parrotforums.com/threads/bird-safe-fresh-foods-toxic-food-lists-sprouts.24213/
I have never left a bird in the travel cage when first bringing them home. If they don't step up then I open the travel cage in front of their open cage, and stand there holding it until they enter their cage.
None of my birds have ever been more aggressive by introducing them to their cage when I first bring them home. I give all of them a chance to settle into their cage, everything is new to them. All birds are different, and some want to some out and interact right after they get here. Others may take time before they feel comfortable. You should always go at their pace.
Veggies should be offered from the beginning. I have had many birds (including my GCC) who have taken months to start eating their veggies. Don't ever give up! Some birds will start eating them if they watch you eat them. Others may take their sweet time before they try. It is well worth it when they finally realize that veggies are good
My birds all get a fresh dish of pellets/seeds every morning, and they get veggies twice a day. They should always have food in their cage available.
Just want to clear this up...weaned means fully eating solid food, not just starting to.
I wish you the best, and I am so glad you joined us to ask questions.