1. Your dog moves away when you pet his head:
A dog perceives continuous head patting as a signal of dominance, not affection. It also just does not feel good. Dogs prefer to be stroked, particularly on the side of the face, under the chin, or on the front of the chest. They also like having their rumps scratched.
2. Paws and scrapes the ground after eliminating:
A dog doing that is actually engaging in a kind of marking behaviour to advertise his presence - the opposite of trying to cover up the "evidence".
3. Eats feces:
This behavior is commonly displayed by puppies. It is species-typical behavior. There is nothing harmful about it to a pup, who will probably outgrow the behavior by the time he's one year old. But if you find it too objectionable, simply deny access.
4. Eats grass:
Some people believe dogs eat grass to make themselves throw up when they have stomach upset; to self-medicate. Some believe dogs simply like to eat grass and then throw up when they eat too much of it. Both believes have their place. Different dogs have different grass eating patterns. None of them are harmful, so don't fret if your dog throws up after nibbling on grass.
5. Sniffs around "forever" before urinating:
To a dog, urinating is an elimination process and a way of communicating. So a dog has to take in the various olfactory notices left by other dogs before leaving a message of his own. He may even want to make sure that no other pup has previously urinated in the spot he's considering. Thus, it may take some time so be patient.
6. Sniffs another dogs behinds:
If smelling were seeing, humans would be considered legally blind by those in the canine world. Pheromones generated from the glands around a dog's anus let another dog know the identity of another dog.