I posted an article about them a few days ago... I'll link it again. The BIGGEST problem with leopards, is they are horrible shippers, and they are benthic feeders. That means they usually break their jaw trying to dive into sand in a shipping bag that has no sand. If and when they get into an aquarium, it needs ample copepods for it to survive on indefinitely. It may or may not eat frozen, most do but be prepared for it not to. Especially at first. My leopard came in already eating frozen from an LFS, the black leopard is the sole survivor of a trio ordered online. One DOA, one dead in 24 hours. Noir, made it thru QT and 3 months in the display before touching the first piece of frozen. I supplemented pods once before getting her, then twice until she switched to frozen.
As far as aggression, they can live together so long as there is only one male of each species. Multiple females of the same(and different) species can live together as long as care is taken to separate the ones that transition to male. Aggression towards other fish is non existent unless provoked in my experience. My melanarus will harass my two leopards occasionally, they are much more agile tho and will usually put a tooth in his side and he backs off.