I think you might end up with problems with a pair of brichardi in a community tank. Even a 55 gallon. You could try it, but if you did it wouldn't hurt to have a back up tank ready to move them into in case it doesn't work out. IMHO, they make great fish for a species only tank.
Really, most of the Neolamps are pretty rough when breeding, and the brichardi have been known to take this to the extreme. Not saying that it can't be done, but most of the time its a recipe for disaster.
If your going for the non-jumbo cyprichromis (Cyprichromis untinta), then I might think about bumping up the numbers. They seem to do better is larger groups as they are a bit skittish anyway.
The N. multifasciatus will probably be fine. Multies are a hardy fish, and quite fiesty for such a little fish. So long as enough rock work is given to the rock dwelling fish so that they will not try to take over the shells, they shouldn't harrass them too much.
Julies are some of the most entertaining fish I've ever seen. You should love these. I would try to get one of the dwarf species (ornatus, dickfeldi or transcriptus) if possible as I've heard that they are more mellow than the larger ones. (may want to check my spelling on the scientific names )
Having more than one spawn at the same time being successful is going to depend on a few things. One of the biggest is going to be the rockwork or decor in the tank. The more rocks, caves and other things that will break up the line of sight between where the fish might choose to breed the better. Also knowing your fish is going to help you in setting up the tank. Cyps are mouthbrooders that spawn in open water, so they don't need any caves for breeding, where the multies are going to need shells to be secure.