We bought Buff Orpingtons last year. They are the first chickens we've owned, but I would recommend then to anybody. They are wonderful birds; they look beautiful, have (mostly) friendly personalities, and lay great eggs. They are winter-hardy, which was important for us way up here in northern Wisconsin. They also are good mothers, if we decide to let them hatch any eggs.
If your parents do allow you to get some, be sure to order hens only. If you are worried about your neighbors now, then you definitely don't want any roosters in your flock.
If you want enough eggs for a family of four, then three or four chickens should be more than enough... Four chickens should lay about two dozen eggs a week in their prime. With that few birds, you only need a small coop.
I don't think I would start out with the idea of selling eggs. More birds means a bigger coop... Each chicken should have at least four square-feet of floor space in the coop, and ten square-feet in the run or yard. So, for four chickens, you're looking at a coop at least four-foot by four-foot. Imagine you and your sibling stuck in a tiny bedroom!
More chickens would also mean more feed to buy for the five-ish months before they start laying. Once they do start laying, depending on prices in your area, if you sell a dozen eggs a few times a month, you should be able to pay for feed for four chickens.
Good luck, and keep us posted.
