A good place to start is Getting Started Raising Chickens. Read all you can.
Naturally, a couple of biggies is to have a coop and run prepared for when it's time for the chicks to "go outside". About 4-square-feet per large fowl inside the coop. About 10-square-feet in the run per large fowl. I think four to six weeks is pretty standard for the chicks going "outside". If the coop is baby-chick secure and your climate is warm enough they could go out earlier than that...
Rooster... Helps watch over the flock. Alerts hens to danger and to new found treats. Fertilizes eggs. Can be friendly. Can be aggressive. Can be quiet, can be noisy. Another mouth to feed and house that doesn't produce eggs. For what reasons would *you* want a rooster?
Free range vs. secured run... No security for free ranging chickens. Are there many predators in your area? What types are they? Chickens are easy prey. Secured runs help protect the chickens but sometimes predators still make it into them and wreak death and destruction. Dogs are very bad on chickens...it's a sport to (most) of them, so predators are not necessarily "wild" creatures.
More chickens... Until you have a better understanding on what is involved in taking caring of the chickens that you have and their space requirements I would not get more. During the time that you learn the basics you can study up on breeds and form your own opinion of which ones you wish to add.