There's some good advice here.
I want to share a photo of a raised bed shape that I've started building.
That's 10' by 10' with a 2'x5' pathway inside it. I built the entire bed using 5 2x10x10 boards. It's filled with half "dirt" and half compost. These will grow whatever we want and will do it well.
As for the chickens, we have in the past had the same problem with our chickens destroying our hard work. It's the primary reason why I no longer allow the chickens to free range.