Sheba and Atticus both sound good, but as others have said, I think before you make any decision you and your family need to meet the dogs and spend a little time with them to know which is the right fit for your family, or if neither is.
We have two blue heelers and absolutely love them. We had a fantastic blue heeler when I was growing up, and when it came time for us to get a dog, it was an easy decision. We skipped the first litter of heelers someone had available as they just didn't feel right, but the second and third litters, we took one from each after spending a couple of hours with them. They were only two and four weeks old when we picked them out, but we waited to bring them home till they were weaned, about six weeks or so. They are from long lines of working dogs specifically bred to NOT nip, and their parent dogs were extremely well behaved. They are actually half brothers, same dad.
Pics and someone else's description of the dog just won't really let you know how you'll bond with the dog and it with you. We were very quickly sure of which puppies we wanted, but spent a long time with each to be sure. Funny thing was, every single person who came after us to pick puppies always wanted the two we'd picked out!
It sounds like you're ready for a dog, now is the hard part of meeting a few and sometimes having to decide "no, that's not the right fit." With young children, it's especially important to find that right fit for your entire family.
All that said, I think Sheba or Atticus have a very good chance of being the right dog for your family. It sounds like they're more laid back, not as energetic as our full-blooded blue heelers!
The Australian in each of them should give them a lot of intelligence, which makes for better and easier training. Just make sure you always are the alpha. If you're not sure how, get some dog training books from the library. It's not difficult, but it does prevent your dog from ruling your house and family.
Good luck and happy hunting.
