Highly recommend going with higher ratio of females to males, or you'll not only have males fighting, but females dropping dead of exhaustion. Once those boys get on a spawning kick they are relentless. At LEAST 3-4 females. Or as mentioned before, ALL males. I have corydoras in with mine--I think honestly that the synodontis would be an expensive unnecessary addition with aulonacaras. They are better with larger cichlids.
Peacocks are mouthbrooders, so the females will go 3-4 weeks with those little eggs/fry in their mouths. There will also be cross-breeding, so unless you pull out any surviving fry, don't sell or give away any of the offspring. That's a major problem even at small LFS--they'll have a tank of "mixed cichlids," which are usually mbuna and peacocks. Got one.
No live plants, they will certainly wreak havoc. Large or giant ones are nice for blocking views. And do some rockwork for them; they need alot of hiding places, it's just a security issue for them. Good luck!!!
Oh, and they are major earthmovers. The males will clear out an area, it's amazing. Shell by shell or sand mouthful by sand mouthful, they'll go all the way to the glass. This is the dancing circle for the mating ritual. Therefore you need to be cautious in how you place rock, or a rock could break glass. Good luck!!! They are awesome fish.