I would continue frequent water changes to bring the nitrite level down to under 1ppm if possible. Cycling can take up to 6 weeks if you are starting from scratch without seeding from existing tanks. I run 2 filters in my 55 gallon. An Emperor 400 and a Fluval 305. I would recommend the 405. I've had no problems with my 305.
Although I am not a stocking expert so I'll let someone else help you there. I do know the Kenyi's get very aggressive as well as the johanni's. Those mbuna are best kept in ratios of 1m to 4 or more females. They aren't pairing fish. Assuming that tank is 4' wide you should only keep a max of 3 species of mbuna in ratios that I mentioned above. Some people have mixed all different cichlids from different countries with some success however it seems in the long run it doesn't work out or the fish don't thrive.
Although I am not a stocking expert so I'll let someone else help you there. I do know the Kenyi's get very aggressive as well as the johanni's. Those mbuna are best kept in ratios of 1m to 4 or more females. They aren't pairing fish. Assuming that tank is 4' wide you should only keep a max of 3 species of mbuna in ratios that I mentioned above. Some people have mixed all different cichlids from different countries with some success however it seems in the long run it doesn't work out or the fish don't thrive.