If your pup lunges: If your dog is going after something while on a walk — another dog, a car, a skateboarder, for example, be proactive. Try to redirect his attention with a treat before he has a chance to lunge, and increase the space between your dog and the target. Stay alert and be prepared before the target of his frustration gets too close. This type of behavior may be more common in herding breeds, but any dog can be startled by something he’s not used to or finds exciting.
Discourage him from biting or nipping. Instead of scolding him, a great way to put off your mouthy canine is to pretend that you're in great pain when he's biting or nipping you. He'll be so surprised he's likely to stop immediately. If this doesn't work, try trading a chew toy for your hand or pant leg. The swap trick also works when he's into your favorite shoes. He'll prefer a toy or bone anyway. If all else fails, break up the biting behavior, and then just ignore him.
Help him relax when he comes home. When your puppy gets home, give him a warm hot water bottle and put a ticking clock near his sleeping area. This imitates the heat and heartbeat of his litter mates and will soothe him in his new environment. This may be even more important for a new dog from a busy, loud shelter who's had a rough time early on. Whatever you can do to help him get comfortable in his new home will be good for both of you.
Submissive urination is a normal way for your puppy to demonstrate submissive behavior. Even a dog that is otherwise housetrained may leave dribbles and puddles of urine at your feet when greeting you. Excitement urination with a puppy is usually caused by lack of bladder control. The puppy is not aware that he is urinating; he's just excited and any punishment will only confuse him.