I disagree with why renegade, red zebras (if we mean metriaclima estherae) are not very aggressive, usually on par with yellow labs (which are arguable the most docile african cichlid). It is true that you can get a oddball fish that will be highly aggressive, but overall red zebras are not aggressive. I have kept many individuals from this species and they are great.
As for your intended stock. You could make the original stock work if you have enough caves (as previously mentioned), but I would personally stay away from auratus - they are one of the more aggressive. Also, the johanni will probably rule the tank, but I don't think you will have any problems with your second round of stock.