What are the dimensions of your coop? Depending on that, you might be able to get more birds, which in my opinion is what you want to do. Also, when you say start with 7 chickens, does that mean you would add more in the future? The only reason I ask is because adding chickens to a flock can be an extremely difficult process, and if you have the space for more birds, then you should go ahead and go for it! Taking care of chickens is all the same...you still have to go out there to feed, water and clean, so it doesn't make much difference in care when it comes to numbers. Chickens are not needy animals, and their difficulty doesn't increase in numbers.
As for the breed, australorp is a very popular beginner bird. They are reliable layers of large brown eggs, and since they are a heritage breed they should be able to lay eggs for a longer period, unlike some of the hybrid breeds which only having a laying life of 2-3 years. If you can buy local, then do that, as it will cut shipping costs and decrease your chance of losses to practically 0. If you are located in a hot area or cold area, make sure you get birds that are tolerable of that climate. Australorps are pretty hardy birds on both ends. So you should be safe. Other suggestions from me would be Rhode Island Reds, Buff Orpingtons, or Easter Eggers. Best of luck!!
