Take a look here: backyardchickens.com
-you can expect slightly less than 1 per day per hen.
-If you can free-range them feeding is nearly free. You may need some feed to entice them back into the hen house.
-predators will get them if you don't watch them. you need to make sure they are back in the "barn" at night.
-depending on where you live you many not be able to buy fewer than 12 chicks at a time. Many locations have laws to avoid them being purchased as cute easter presents and then forgotten.
I'm thinking about doing the same thing.
It's grandma, but you can call me sir.