Chicken coop size help

Because they may spend time confined to the coop/run area you need to allow as much space as possible in that area -- a good minimum is to plan at least 4 square feet in the coop (not including space occupied by feed, water, etc) and 10 square feet outside. That being said, the more room you give them, the less likely you will have issues resulting from them feeling overcrowded so more is always better. Additionally, if there is any chance (ie you are not restricted by regulation) that you may want to increase your flock (hint, except when legally unable to do so it nearly always happens) it is, again, best to build bigger than you think you need now vs. trying to remodel later to make more room in the coop to allow for more birds.
As to keeping the birds home -- clipping one wing's flight feathers can be very helpful in preventing them from going over the fence. In addition to the potential of the neighbor complaining, they are also at risk of injury or predation if they are outside the protective boundaries of your yard.

 

You may need a enclosed run with a top, to keep your birds from visiting the neighbors, etc. Four foot fences are pretty low to the breeds that do fly (silkies do not), and also very accessible to predators who can jump, climb or launch an attack from the sky. By clipping wings you take away one of their defenses , otherwise all they can do is run & hide.

 

G’Day from down under bryantflock Welcome!

As you have already received some great advice, I will just wish you all the best.

I hope you enjoy being a BYC member. There are lots of friendly and very helpful folks here so not only is it overflowing with useful information it is also a great place to make friends and have some fun.

You might want to also pop in and say hello on your local thread: https://www.backyardchickens.com/f/26/where-am-i-where-are-you ‘Find your State’s thread.

If you would like to share pictures and stories of your flock, you have come to the right place. BYC’ers never tire of these and do not back away slowly or commence eye rolling when the photo album or home videos come out

 

Hello from Kansas, bryantflock, and ! Pleased to have you in our community! Looks like you've received some great advice from Ol Grey Mare so I'll just say best wishes and thanks for joining BYC!