You need to get LOTS of snail shells with about a 1-1.5" opening and then get yourself some n. multifasciatus shellies. These are the smallest and are lovely. You could keep a small group in there and watch them multiply Stick to a single male with several females. You may find that, as they breed, you get certain fish (usualy males) getting bullied until they are spending all their time in the top corners. Take these individuals out and sell them to your LFS or something. I would re-arange the slate you have, maybe take some out, to make the bottom area as free as possible from rocks but keep a few to split the tank up into, say, 2 sections so that you can provide two seperate 'territories'. Put plenty of snail shells in both sides and let the fish choose where to set up their colony. You'll find they rbeed readily (well, IME anyway). Also, I have never had problems with mutlies uprooting plants but I personaly don't like plants in a shelly tank anyway. Other shell-dwellers, especialy larger ones, may be mroe inclined to cause damage. Oh, bTW, you can use shells from the 'escargot' you get at supermarkets.
Here's a good link about shellies as well:http/www.cichlidrecipe.com/shellweb/