I'd post pics if I knew how. Will have to get my son to give me a hand.
But, yes, your tank looks ok for what you intend, depending on the number of fish, and the number of species you want to keep. I try to have 2 caves, crevasses, and hides for each fish that will need or want a territory, so, IMO, you may want to try adding a few more in your tank, but without adding much more weight.
As for fish, in a 55g, I would limit it to 3 species on Mbuna with 1m/3f for each species. That's a good ratio for breeding. The easiest Mbuna to breed, in my experience, are Yellow Labs (Labidochromis caeruleus), and Rusty cichlids (Ioddotropheus sprengerae). They both breed like guppies, and will soon overstock your tank if you don't have a way to get rid of your fry. I feed mine to my oscars when they reach about 1" unless someone wants to adopt them.
