Keep in mind, that all info I have given over the years was with a long term captive specimen. I bought her aprox. 7 years ago, from a guy in Chicago, who'd had her since she was aprox. 14" long. How many years he'd had her, I can't remember.
There may be a lot of truth to the guys that tell you they're highly aggressive, when they first get them and that would mainly be due to the fact they're small juveniles. As with any small, wild animal, they're gonna instinctively be aggressive. I just bought a 14" - 16" hatchling Burmese Python and can't take him out with getting tagged at least 5 times. It's just baby nature.
There may also be truth to the statements flying around that they don't do well, when first put into captivity...I'm not sure. The guy I'm trading mine to has had two juveniles in the past year. He still has one and the other died due to a pump malfunctioning and spilling oil into the tank.
When it comes to being kept with other Morays, I wouldn't have a problem keeping an established one with any Moray. From all accounts I've read, they're not much of an eel eater...but, that's all just my opinion and done so at your own risk. When I first got mine, she went into the tank with a well established Whitemouth, who tried to show her who was boss. It took about 20 min, of her not backing down, before he knew who wore the pants.
That 6 Dragons, in an outdoor pond sounds like I'd be in heaven, if I saw it and would probably set up a tent, next to the pond and only leave if forced. I'll eventually have more Dragons...that's why I'm not too upset about letting mine go.
Anything else I can help with, don't hesitate to ask, guys.