I'm getting a baby quaker on Thursday - need advice!

Welcome Glass Cat and your new little one!  No worries about the long post- we love details and we love to talk Quakers  Biteybird has given you some great answers to your questions, so I will see what I can add--

1) When I was growing up, I had a cockatiel (my parents still have him- he's 24 now)... and his level of intelligence did not prepare me for having a Quaker.  I've found myself consistently underestimating our QP's intelligence as long as we've had her.  They are very sensitive and perceptive little birds, with tons of opinions and preferences and a strong need for social interaction and a healthy flock dynamic.  They want to be part of everything, and will feel excluded if they are not involved.  They need consistent eye contact, and they never stop learning.  On that note, getting in the habit of praising good behavior and ignoring bad behavior is a good thing to do as soon as possible.  Treat them like a family member-- for example, we greet Cupcake enthusiastically immediately upon arriving and before leaving, and this is clearly very important to her.  As biteybird pointed out, understanding their hormones and the nature of the 'honeymoon' period before sexual maturity kicks in is really helpful.  You don't want to get blindsided by that-- I know cockatiels can be quite hormonal as well (ours was a nightmare for the better part of a decade), so I'm sure you are familiar with these concepts.  Discouraging hormonal behavior will most likely be an ongoing battle with your QP, but it can be very manageable if you stay ahead of it.

2) I am not very knowledgable when it comes to raising baby Quakers, honestly, as we got Cupcake when she was already 9mo old...  So in my limited knowledge, I would say do what feels right-- but you definitely want to ultimately end up with your bird in the part of the house that gets the most exposure to the family, so they feel most included in everything that is going on.  Biteybird makes a very good point about the sleep cage, however.  Our QP has a sleep cage that we carry into a separate room at night so she can get uninterrupted darkness and quiet, and we can go about our business without having to worry about disturbing her.  I tend to think this is the best approach.

3) As biteybird notes, we are a fan of the Harrisons brand of pellets, largely because they are organic.  They can be ordered online if you can't find them in a store nearby.

4) What biteybird said...  Can't stress this enough-- these birds can sense your emotions, and are affected by them.  As you probably recognize, birds are most comfortable around people who are most comfortable around birds.  And they know if you are angry, or anxious, or distracted.  This can lead to negative behavioral feedback loops, as you could be frustrated or anxious, and the bird could misbehave as a result, leading to further frustration or anxiety, etc..  It's an easy trap to fall into for some personality types.  The bird will appreciate a consistent, calm, positive demeanor, and while I do think they know on some level when you are faking it... it's a lot better than not  At any rate, try to be mindful of how they must be feeling in their alien surroundings, be empathetic, compassionate, patient... and talk to them extensively.  All of this being said, it's important not to spend more time holding/cuddling/focusing on them initially than you will be able to maintain on an ongoing basis.  Be as consistent as possible.

5) Honestly, I use Amazon Prime for just about everything, but I know others on the site have other sites that they prefer.  I will let them chime in.

6) Not much to add to what biteybird said here.  

7) I will second what biteybird says about establishing a bond with each member of the family.  And even if you do this, it is possible that the bird will pick a favorite and become protective or jealous.  This can be worked through, however.  Cupcake, once hitting sexual maturity, became aggressive toward my wife and stepdaughter, and it took the better part of a year to resolve this (and lots of one-on-one time between her and my wife)... but now she loves everyone, and there is virtually no aggression.  Look for signs of developing aggression and intervene and take immediate corrective measures (if your bird displays aggression towards someone, make sure they spend some focused time together if possible, have them do the "good" things, like giving the bird treats, letting them out of the cage, etc..  this is a vast topic on which there are many threads on this forum as well as many articles out there on the internet if you want to explore further)

I too am sure I forgot some things here...  good luck and let us know if you have more questions, and keep us posted on how things go!!

I know everyone is talking about the "ear-splitting" Quaker squawk and I agreed that it was indeed noisy until I adopted Rocky 'Too and now I think the Quaker squawk is just a pleasant noise, compared to a cockatoo screaming for an hour without stopping. LOL

Now, to the Quaker body language, based on my two: slicked down feathers mean the bird is frightened and might bite. Fluffy, but not overly fluffy, just relaxed fluffy, means the bird is comfortable and happy. Overly fluffy is often a sign of hormones and feeling romantic and it's best to set that bird on a perch and avert your eyes lest you become his/her love toy, which is embarrassing and can eventually lead to biting and attacking behavior if not nipped in the bud. Quakers usually give you a warning before a bite but not always. They're moody. My Clyde will demand head scritches and then bite me for giving him head scritches. You just have to be prepared for that sort of thing.

Quakers choose a favorite person but our two also accept the presence of the not-favorite person. It takes a while for them to settle on who's the favorite and they might be difficult to get along with if you're the not-favorite while they're making up their little minds. They're also greedy and a sunflower seed or other rare treat will go a long way to soothing their tempers.

You can buy toys and food aimed at cockatiels and that will work fine for a Quaker, but don't be afraid to get toys aimed at bigger or smaller birds, too. My smallest is a budgie and my biggest a cockatoo, and when a bird gets bored with a toy, I give it to a different bird without regard for the size difference. My budgie's favorite toys are usually the big ones. The tiels will play with anything. One Quaker loves bells and noisy toys and the other hates those same toys. They also steal food from each other's cages without regard for the size. So if budgie treats are on sale, don't be afraid to give them to a Quaker. Moderation in all things.