I haven't kept or bred these guys but I've heard that these guys are harder on each other than A. rivulatus. They're omnivorous.
Here's what CRC says about their habitat:
http://www.cichlidae.com/species.php?id=2308
Habitat: Small rivers that flow from the western part of the Andes into the Pacific Ocean. These small rivers are formed by big gradient courses of water and quiet pools, Andinoacara stalsbergi is normally found in the pools, the rivers may increase their flow significantly during the rainy season. The pH of the water is on the alkaline side with a value of 8 or more common, water is also hard. The temperature can be cool during the rainy season and warm up in the pools. No aquatic plants are present but algae is found growing on the rocks. Regularly, the susbtrate is composed by sand, rocks and boulders. Andinoacara stalsbergi are also found in the wider slow flowing tracks of the rivers close to their entrance to the sea, where the substrate becomes muddy.
They are open substrate spawners. I'd bet that they'll start spawning at 3" or so. When they start courting, I'd do a big, cool water change to simulate the rainy season...
Matt