Other fish you could add:
Tinfoil Barbs, Silver Dollars, Blue Acaras, Black Ghost Knife, Geophagus and/or Gymnogeophagus. Basically any large robust fish that isn't too aggressive, Severums are on the low end of the cichlid aggression scale and generally will break fights up.
Don't listen too much to books and stuff, fish are incredibly adaptable and most fish live happily at pH 7 as long as the water is clean. Also note that different pH levels have an effect on ammonia, so if you do raise your pH using dead coral just be aware of your Ammonia, Nitrite etc