Chickens will hang around, guinea hens readily revert to the wild. Chickens can nail a fly on the wing, and they are on a constant search for tasty bugs. I would go with the chickens, you get eggs, a recycling garbage disposal, and meat if you are willing to do the work. The machines at Tyson run pretty cheap and there is a lot of work turning a chicken into a bucket of KFC.
There are a lot of books on molecular gastronomy but I don't have a favorite.
Didn’t realize guinea hens revert to the wild. Chickens sound good. I love eggs.