Greetings, I am a professional dog trainer, and I will see if I can help out some. First, the potty problem. Do you have a small dog crate for the dog? How often does the animal eat? and What does he eat? Is the dog's water available at all times? How often do you take the dog out? Once, I get some answers to these questions, I will be able to give you some helpful tips. Now, the jumping and biting problem. The dog needs to know who the alpha animal is in the house. ( It is you/ and/ or, your husband) Even though the dog is small, it still should not be jumping. (That is a BIG no-no!)Keep a leash on the dog, yes, in the house to gain control over the situation. The 3 year old should have no control over the leash,at this time, and should not play with the leash in anyway. The leash is to gain control over the jumping, immediately, when it happens. The leash also allows the animal to be socialized in a proper manner. When you are sitting in the room, put your foot on the leash approx. 4-6 inches, from the collar, and command the dog to lay down, and to relax, or just to lay quitely, chewing a chew toy/bone. The leash also allows everyone to get into the action, even your 3 year old.,by teaching the dog to "come". What you, and your husband?, and your 3 year old can do, is sit in a circle (more or less) with the dog in the miiddle, and 1 at a time, you say "COME, FLUFFY" (I don't know the dog's name, so, I am just using the name Fluffy). The 1st person whom is calling the dog, has the leash in front of them, the dog is in the middle, and the person says strongly 3 times only, Come, Fluffy, Come. After the 3rd time calling the dog, you take the leash, and pull him/her towards you, and say , " Come ,Fluffy, Come. You come when I say Come!" Then you sit the dog down , facing the next person,throwing the end of the leash the next person's way, and repeat the above steps. Repitition is the only way to properly train your animal. The 1st year of a dog's life, while they are a puppy is the hardest. 6 months - 1 year is the absolute most crucial. By gaining control of the puppy's behavior, it is the first step to having a great friend, companion, and dog. I hope I explained what I am trying to say, in a way that you understand. Feel free to email me, with your questions, and concerns. I will do my best to help you out. When the puppy bites, take your 2 fingers (pointer finger, and middle finger), and come down on the dog's snout and say, STRONGLY, "NO BITES! NO BITES!" Be patient, yet persistent. J.