Yawning may indicate anticipation or stress. It increases heart rate and blood flow to the brain. Filling the lungs with oxygen and removing carbon dioxide. In fact, it helps a dog energize his body and gathers his wits.
Paw lifting is a dog's way to call your attention. It may be an invitation to play or a means to tell you something else.
Mounting or standing above another dog by putting front paws on the other dog's back means asserting dominance. It isn't just a male characteristics for females do it too. Mounting is more often related to social status than to sex.
Raised hackles indicate arousal, either because a dog is frightened or is challenging another dog. Smooth hackles show a dog is calm.
Relaxed ears mean that a dog is calm. Erect ears show that a dog is alert and attentive. Ears that are up and forward mean a dog is challenging or being assertive or aggressive. Ears that are laid back indicate that a dog is worried or scared.