I think I'd start by trying to get a rough estimate of quantities of waste and gas you can produce. Based on the quantities you describe (toilet wastes from a single family residence, a few chickens and some glycerol) I'd guess you probably can't generate enough gas to justify the cost of a CHP system, but certainly enough for cooking, and maybe heating water. Have you tried my online calclator
? (Caveat: It is somewhat dated, based on an older design that I have since redesigned, but it should still be useful to give you a rough order of magnitude idea.)
What I find myself recommending to most people is to first do some bench scale tests (one or more jars in a temperature controlled water bath) -- do some direct small-scale experimentation before committing to anything larger. Another advantage of that is what you learn about the digestion process, how to keep a larger system going, keep it from crashing, etc., all without a major investment.