No need for a roo. The hen ovulates (just like all animals) only they do it nearly everyday. Without a roo, they are not fertilized and will not grow into a chick, even if kept warm.
A roo will not get a hen to go broody, which means that she decides that now is the best time to raise a clutch ( a group of eggs). She will take eggs at this point. If you don't have a roo, and you want chicks, you need to get or buy some fertilized eggs. She gets in a trance like, a bit grouchy and won't get out of the nest. At all other times, hens jump out of the nest, with the attitude, whew, got rid of that, I am not taking care of it, I am out of here.
This is kind of the neat part. Fertilized eggs can sit at room temperature for several days, up to 10, and then get place in a incubator or under a broody hen, and only then will they start to develop.
You also don't need to keep your eggs in the fridge. They stay very fresh at room temp for many days.
Welcome on board, you are going to love this hobby. Mrsk