You only need to stir the sand if you have more than four inches, and if you don't have any live plants. Otherwise it's not really necessary.
For cichlids, I like German Blue Rams. I am going to be getting two in a few months. You just have to make sure to put them with other dwarf cichlids, otherwise they might get beat up.
If you want semi-aggressive, you could have 6 Indian Dwarf Puffer fish. They are completely freshwater. Then you could add 6 or so Freshwater
Bumble Bee Gobies. They are the only thing that won't get eaten by the puffers. If you go this route, make sure you have the tank heavily planted