Can anyone tell me what they're like- temperamentally?
They're most of the time peaceful, especially towards the other species. When they start breeding though, they're like 2 male bettas, that is friendly to each other; guarding the same nest, they'll chase out any other fish and sometimes even try to attack you, or at least showing aggression from inside the tank if you're getting too close.
If there's an ideal gender ratio?
Not really, but they do best with a group of 4-5 or more. Unless they're a proven breeding pair. Not to mention, it's really hard to sex them if they are not in 'breeding-mode' or if they are not fully grown.
If they prefer company or if they're more independent... will they "school"?
Yes, they will school. However with too few of them, the dominant one will bully each other.
Is there a little tetra/schooling smaller fish that they might be able to live with?
I've used cardinal and neon black tetras. They're alright when the angels are still small. However, when the angels are fully grown, they might snack on the tetras. Emperor tetras would be large enough not to fit their mouth, but due to the size, the school may need a bigger tank. Cardinal tetras -may- be alright though.
Is there anyone with contacts with breeders? (I'm a snob and want fancy pants show ponies in my tank)
Can't help you on this one here. Sorry :(