I agree with Kayla’s Mom.
It sounds like the ‘rocking of the head’ is because your puppy is still so young, it doesnt have the proper neck muscles. This is why you should always wait atleast until 8 weeks of age to take the pup from its mom. This is a very important growing stage in her puppy hood and could really benifit from its mom and litter mates at this time. But since its a bit to late for that, i would just make sure that she gets the proper nutrition and vaccinations that will help your pup live a long and happy life.
As for the feet, i wouldnt worry about it. No two dogs are the same, this pup might just turn out to be smaller then your first pit and thats why the feet are smaller, or maybe its just because shes only 6 weeks old. I hope you enjoy your new pitbull pup as much as i am!