That's a pretty good size for cichlids, depending on the agression level and adult size of your fish, you could have around 15 4-5-inch fish total.
With just about every mbuna cichlid species you'll want to aim for 1 male to several females, as in small groups the males will fight over territory and females, and you need more than one female so the male doesn't pester her to death. A few good beginner species are yellow labs (labidochromis caeruleus), rusty cichlids (idotropheus sperengae), and pseudotropeus acei.
For proper stocking, I would pick 3 species and get 5 of each.
You'll want a finer substrate than traditional gravel, ie: sand or crushed coral, because they like to dig constantly. You'll also want to put in lots and lots of rocks so they can claim territories, here's a link to a lot of members tanks to give you some ideas
http
/www.fishforums.net/index.php?showtopic=146796 .
Just find 3 species you like and then post and we'll let you know if they are compatible or not. I definately recommend fishless cycling for these guys as they are generally a little more expensive than community fish. And then add them all together or add them the least agressive to the most. If you have any more questions please ask.
Oh, and welcome to the addictive world of cichlids.
