Well it sounds like they weren’t being fed properly before you got them or they wouldn’t have wanted to inhale their food. As they learn that it will always be there at that time of day and they aren’t going to starve they will calm down and eat slower. Also when other dogs are around it’s competion so they will eat faster. As for the aggression with each other. Some people will say you shouldn’t feed dogs right next to each other. I feed mine right next to each other and if I don’t watch them they share bowls lol. I think if you just keep monitoring them when they eat and make them understand that is not allowed they will get better with time. When you notice it starting dominate the food and eventually it should show them you are in control and that is not acceptable behavior. Also take them to obedience so they understand sharing with other dogs. It will take patients but if they are smart like you said they will catch on.