You don't have any serious problems but there are a few "issues" to resolve that will improve things.
First off I should have mentioned this in the first post, Domino damsels are among the most aggressive ,nasty and downright meanest of the species. In all honesty, you should only keep one in a tank that size. Personally I wouldn't keep them in anything other than a large tank with other aggressive species, large wrasses, triggers, lions and such. They can actually bully a more docile fish twice their size until it's dead. That will be a large part of your problem. With damsel species it's really hard to tell if the behavior you describe above is purely mating or simpley one showing submissivness towards the other. The more hiding places and territories available the less aggressive the behavior will be. As long as the more dominant of the two does not literaly attack the other you might be able to wait it out. If the aggressive behavior gets worse, one should definately be removed.
The scooters behavior is quite normal for a "casualty of war". It's their way of hiding when feeling threatend (or at night to sleep) but as long as it does not continue for much longer it will be fine.
The only other issue is the food. Adult brine unless heavily fortified or "gut loaded" prior to harvest is basically nutritionless. The color of you fish aside from stress is directly related to the food source. The more vitamin enriched the healthier the fish. A good suggestion would be mysis, fortified marine flakes and soaking foods when possible in a liquid marine vitamin a few times a week. I would also do a search on this site for "blender mush".
I would also suggest you read up on <<quarantining>>
all new arrivals prior to adding them to the display tank.