As far as food is concerned, find out they are using to wean and start with that even if it is a pellet or seed mix that you might not prefer. So much will change in the life of your baby bird that it will be a comfort to have familar food. This can be changed gradually starting in a few months, once your s/he is all settled in with you. You can immediately start offering clean, fresh or cooked vegetables (no salt and if possible pesticide-free) every day. Experiment with different shapes. The humble carrot can be given as sticks, coins, tiny cubes, bigger cubes, or Rhubarb's favorite, the long curls made by a peeler. Even if the vegetables aren't touched for at first, keep giving some every day. The sooner a bird starts "experimenting" with healthy foods the better. A month ago our vet said that Rhubarb is one of the only Galah's in his practice who is not overweight. This is very intentional on our part because Galahs are prone to obesity and fatty tumors. Actually, weight beings me to my next thought.
Ask that your baby not have wings clipped if you have a safe space to practice flying at your home, like a bedroom where you can close the door and keep out other pets and very young children (if any live at your house). Besides the health benefits of learning to fly properly, it is a huge confidence booster for a bird. Confidence and regular exercise will head off so many behavioral problems before they begin. In this one small way birds are a little bit like tiny dogs: Many of their behavior issues are from fear and uncertainty or lack of exercise. That's about where the similarities end though. Dogs are predators and birds are prey animals. Everything a bird does is from the perspective of an animal that has been hunted for thousands of generations and depends on it's flock for survival.
If you aren't sure of which soft-cover book to get, one that is a bit older and easy enough to find used is called Sally Blanchard's Companion Parrot Handbook. It is a classic. Some of the information on diet is a bit dated but the behavior insights are absolutely pure gold. I've had companion parrots most of my life and I learned stuff reading her book.
On the topic of behavior, do consider using your travel cage as a sleep cage in some quiet corner of your place. We had a lot of difficulties with Rhubarb at first because she so badly wanted to be part of everything that when we covered her cage for sleep she'd cheep and cry to be allowed into "flock" activities. We ended up buying her a second, smaller cage and tucking it into the doorless closet in our bedroom. It took a few years but now she happily flies to her sleep cage when we say "Night, night!?" Like little children, birds can get cranky when they don't have enough sleep and a regular bedtime. They need about 12 hours of dark time every night. And putting them to bed around the same time helps them make their own "winding down" routine in the evening before they change cages. It also provides a quiet retreat for sleep that doesn't feel like isolated punishment. Bedtime should be whatever works for your schedule. We have it at 7 pm so we can have evening time to ourselves but for someone I know, bedtime for birds is always at just before midnight because that works with their schedule. A sleep cage is something I wish I'd known from the first day so that routine could be started early. To set up a sleep cage I would a recommend a bowl of dry food (same kind as in the day cage), a comfortable perch like the platform
@Shezbug mentioned and every evening, some fresh water.
If I think of anything else, I'll be sure to come back and share!