I agree fully with what Sue has said.
Regarding cichlids, it would be best to just keep one species, as each fish or pair would need its own territory, which would be at least half the tank. Mixing them can be done but there’s never a guarantee of peaceful coexistence, and definitely not if they breed.
There are a few small species that are peaceful enough to live in a tank with non-cichlids. Kribs aren’t really one of them if you have a pair (might happen, might not), but one on it’s own will probably be peaceful enough, with space, as it will settle for the other fish staying out of its way. But there’s always the chance of the hormones flowing and the fish coming into breeding condition, and defending a territory while waiting for the opposite sex to swim by...
For soft water look into Apistogramma, Cleithracara (keyholes), Laetacara, Nannacara and Bolivian Rams from South America, and Anomalochromis from Africa. These are all small and very peaceful (for cichlids) towards non-cichlids. They should all work very well in a community... they will probably breed if kept well, but they won’t annihilate the other fish if they do...
For something a bit bigger you could try Thysochromis or Pelmatochromis, both from Africa, although not commonly kept and so not easy to get hold of.
Kribs and the other species of Pelvicachromis can also be very peaceful and worth a try, but they’ll be aggressive when breeding.
For hard water there’s only really Herotilapia, the Rainbow Cichlid, which is (almost guaranteed) peaceful.
Mixed Barb tanks actually work very well, and there are Barb fans that keep exactly that. Any Barbs of similar size should all get along together ok.