Generally speaking its not good to mix Malawi cichlids with Tanganyikan cichlids. Aulonocara jacobfreibergi is a bug/larvae eater, Labdiochromis are insectivores both need a little protein, while demasoni is a vegetarian
Tropheus are not a beginner fish, and they are really meant to be kept in large groups, its not only a big commitment but an expensive one. If you are serious about them, you will a need larger tank 80 - 100 gal and 24+ Tropheus.
Neolamprologus brichardi are really fun cichlids to keep, they will form pairs very easily. They are excellent parents, and will have subsquent spawns going at the same time. However they are 100% cichlid and very territorial and in your smaller tank they are going hold all other fish to one side of the tank once a pair forms. You will end up with a bunch of brichardi babies, but the other tank mates are terrorized in the process. They will definitely bully the frontosa, which despite their size can be whimpy in community situations.
As you can see it can be difficult to do a peaceful community tank, they will all be calm until a pair forms! A lot of people want to work with these Tanganyikan substrate spawners, so once a pair does form they pull it and breed them in smaller aquariums. One option is to pick fish that will occupy different areas of the tank, so they are not competing for the same type of territory. In a 55 you can do a couple of the rock dwellers like any of the many different Neolamprologus, Julidochromis, Chalinochromis. and then you can do a different species on the sand, like a shell dweller; "Lamprologus" or exLamprologus. You would put your rocks on the ends of your tank sloping down to the sand. You would have two rocky areas and one sandy area. But with this option, the Tropheus and the frontosa are not going to work.