I have chickens too - and they will eventually eat most of your garden

I Have mine in a large secure run, most of which is paved so that I can keep it scraped clean. They do have an area to dustbathe in.
Most breeds come in bantam size (small) or large fowl size (bigger) and so will lay smaller or larger eggs (funny that

) If you go for bantam sized hens then you will get smaller eggs but the hens will be easier for you to handle and also you will be able to have twice as many.
Large fowl will lay large eggs just right for dipping your soldiers in, but will be a bit bulkier for a newbie to handle.
When you first get your chickens keep them penned in for a few days so that they get to know where 'home' is.
All things to consider.
I have cats too, and they are scared of my chickens.
Also some breeds of hens are more docile than others.
Marans, rhode island reds, light sussex, etc. are all more docile than the mediteranean breeds such as leghorns and minorcas. The hybrid breeds will lay their socks off for a couple of years and then fizzle out.
A good website is
www.pekinbantams.co.uk. Also -
www.poultryclub.org.
Everyone has their favourite breeds and most chicken folk can talk all day about hens (me included). It's such a fascinating subject and watching chooks interact can be one of the funniest sights you can imagine. (oh dear, I think I need to get out more!).