Welcome to the Poultry World!!! Birds are such fun, but can be quite a responsibility also...especially keeping them safe.
When "free-ranging", you will have losses...from wild, or domestic predators. Making sure that you give them a secure place to which they can retire in the evening is a good start. Locked up safe and secure. Chicken tractors are good, and you can find instructions on how to build them everywhere.
Finding birds, is another story. I suggest that you google "NPIP" and your state. It will bring up a list of breeders in your state, who are participants in the National Poultry Improvement Plan program. Then, just start contacting people. You'll probably not have much luck this time of year, as most of us have already culled our flocks for the winter. Spring will be different.
As far as layers go....in order of productivity, the list goes as follows:
1. Leghorns & Leghorn hybrids - the most prolific layers...genetically engineered for enhanced performance. Over 300 white eggs per year
2. Production Australorps - Same...but not quite as prolific as Leghorns. Still over 300 light brown eggs per year.
3. Black or Red Sex Links - Roughly 280 HUGE brown eggs per year. Still highly recommended, as they are hardy birds.
4. All other breeds run abou the same...240-260 eggs per year.
It's all in what you like. I've bred Ameraucanas for years...because they lay wonderful blue/green eggs....but they also purr occasionally, which makes me happy. You'll change your mind a dozen times before your settle in with a breed. But you'll enjoy doing it!