Really if you are new to chickens, I would recommend going with an all hen flock. You will gain some experience with chickens. All hen flocks look a little more to their humans for care. This is the advice I give when asked any new flock owner. There is a learning curve to chickens, and some may die. Some fail to thrive and some are picked off by predators. I suggest that you have a very good fenced run/coop combination. You can free range them, but there is apt to be losses, and for some !!#$!^$%!#@ reason it is always your favorite.
After you have gained some experience, a rooster is or can be a wonderful addition to the flock. For protection, he needs to be at least a year old. Juvenile roosters are not responsible, and generally just trying to breed. A good rooster is calm, pays attention, lets his ladies eat first, will call them over for treats (sometimes imaginary

does the wing dance, and will generally keep between you and the girls.
I would strongly suggest getting someones 2nd or 3rd rooster, who is so nice, he didn't get culled. Those roosters have generally been raised in a chicken flock, and have good understanding of chicken society. I strongly recommend AGAINST keeping a rooster that has been raised with just flock mates. Those roosters do not have older chickens to enforce behavior, and they get bigger than the pullets more quickly and often times become bullies to hens and people both. Roosters can be very dangerous to small children or smaller women. And there are numerous stories of a darling turning into a nightmare in an instant. Inexperienced people often don't pick up on the cues that he is getting too aggressive until a full blown attack.
As for the fertilized eggs: when a hen lays a fertilized egg, that egg is in suspension, the possibility of a chick is there, but it has not started to grow. Unlike mammals, where the egg begins to grow and divide immediately upon fertilization, birds are not like that, and this is the reason.
It takes a bird nearly 25 hours to lay an egg. So if a hen is allowed to do it naturally, she will hide a nest, and lay an egg there for several days. Then when the number of eggs suits her fancy, she will stop laying and begin setting. A setting hen sits flat on the nest, puffs up huge is anything gets too close, and she heats the eggs pretty close to 100 degrees. After 24 hours of being kept at 100 degrees, the egg cells being to divide, and a chick begins to form. This allows all the eggs to be in the same stage of development so that they all hatch on the same day, allowing the broody to stop setting and start taking care of the live chicks.
So if you collect your eggs each day, there is no chance that there will be partially formed chicks inside. In fact, you need rather a sharp eye to even tell if they are fertilized, which you rather like to keep track of when you get the urge to hatch your own chicks.
Hope this helps,
Mrs K