Alright girlie, I'll try my hand at some of your questions (whew, I was tired just reading it! just kidding!) And you're right, it's easy to get hooked on birds!
I have a Harelquin Macaw (cross between a B&G & a Greenwing). IMO, he has the best of both breeds - very comical & very cuddly. He's literally like having a 2 yr old around all the time.
I hand fed Toby since he was 2 months old. It's not recommended that someone who's never hand fed a bird before, much less a large parrot, take on the challenge. Most reputable breeders won't sell a macaw until they are weened. It was ALOT of work and stressful. BUT I do feel that Toby & I have a special bond because of it. On the other hand, you do not need to hand feed to have that special bond with a macaw. That didn't make much sense did it? (I believe Critter is the one that hand fed from an egg) There was another thread on handfeeding, I'll try to find it for you.
I don't know much about the Galahs. They are very expensive in the US. I fell in love with one last year but I can't have a Too with my macaw. Jackie may know more about them.
Can I ask why you are leaning towards a Scarlet? What about that type did you like? What I know about their temprements is that they tend to be a little more high strung & sensitive, even more nippy - they are pinchers. They're generally not recommended for the first time parrot owner. Don't get me wrong, they are a great breed - but you will need to be on your toes with any kind of macaw. They really are a lot of work - I'm not just saying that. It's nothing like having a dog. Toby's more work than all 3 of my dogs put together!
I can find you a wing clipping website but I would recommend taking your bird to the vet or a groomer to learn how to do it. It's not that hard but you'll need to know exactly what to do and it's much easier to learn when you watch someone do it. IMO.
I take a shower with Toby about every other day. In the summer it's usually every day. He has a shower perch on the wall of the shower and I have a detachable shower head. He LOVES his showers and acts like a crazy burd. We had to teach him about the shower though - it used to send him in to major panic attacks. Some people mist/spray (usually smaller birds) or use a sink, etc. It depends on the kind of bird and the bird itself. Showers/bathes are very important though to keep them in good feather.
DNA testing costs about $20-30 I believe. It's not that expensive and it's the only way to know for sure the sex of your bird.
I just posted an article on feather plucking - click here.
Here is an article on sour crop (I worried alot about that when hand feeding)
As far as diet, for a macaw you will need to feed a lot of fruit & veggies along with pastas, sweet taters, etc. Toby is given seed & pellets (free fed which not all macaws can handle because some are seed junkies). And TONS of nuts. I literally have to make him breakfast & dinner every night. Hmpf. There are tons of healthy people foods that we can feed our birds which helps. Most macaws will gobble up a fresh cooked sweet tater likes it's going out of style!
I have an Island cage and we love it. It's top quality and more expensive than most but well worth the money if you're going to get a macaw. They can tear their cages to pieces and it's not worth getting a cheap one because you many end up having to replace it. Here's where we bought ours: Feather Fantasy
We have the Grand Cayman.
I think I got all your questions...let me know if I missed something. I hope some others will respond too....Especially about the cockatoo. I love the rosebreasted Toos and would be green with jealousy if that's what you end up getting!!
Getting a macaw is a huge undertaking so I'm glad to see you're getting all your facts and doing the research!