You aren't going to be able to breed enough live fish and shrimp to feed your fish and get you out of buying food for your cichlids. 1st you're going to have to feed the feeders. Second, it will take more than one, two, or even three tanks to provide a constant supply of food. Guppys, unless you are breeding quality fish, aren't going to drop more than 20-30 babies every 30-40 days. 30 guppy fry will last you a day and a half even if feeding small to medium cichlids.
Shrimp, these can be bred, the larvae are very small and to raise out a bunch you will need to have space and food.
I'll leave the snails to you with no comment. They are easy.
The point is, if you are going to go to the trouble and expense and space to start a hatchery to feed a couple of cichlids in the big tank why not take the money you'd spend on all that crap and buy some frozen food and some quality dried food and be done with it?
Truth is, I sense a bit of a need for you to see your fish kill something. Not that this is such a bad thing. Why not feed commercial food, get the 5 gallon, put some guppies in there and use them for an occasional treat as opposed to a food replacement.
~sigh~
Bill