Here's an update for everyone after having him here for two days. Using a mister, I gave him his first bath. He did a little flapping and preening, then walked over to the edge of his stand and lifted up his foot to get onto my arm for the first time... totally his own idea. I wasn't going to push that yet as I wanted to give him time to accept me first.
Over the next few hours, he stepped on and off my arm 8 times and stayed gentle and affectionate the whole time. After this, I moved my arm to him and told him to "step up"... the usual command I use with my birds. Instead of doing this, he lowered his head close to my fingers, fluffed up his feathers, and made soft cooing sounds... for me to pet him. So I did. He's totally tame.. lets me scratch his head, rub his face, touch his beak and his feet. He's thumped me a few times but hadn't taken a bite at all.
The latest development after all this now is him bobbing his head up and down trying to regurgitate food while he holds my fingers in his foot or beak. This is the ultimate sign of affection with large parrots.. it's their way to "feed" their handler, mate, or their baby birds.
Vocally, he has a hearty, masculine laugh. So far, I've heard him say hello.. hi... hi there... and alright.
I've noticed that he doesn't respond at all when I use his name. He doesn't seem to recognize it at all. So I've renamed him "Nicholas." This big guy is such a pussycat.. he's not a "Rebel" at all.