First off, I would like to recommend two books to you. Boxers for Dummies and Dog Training for Dummies. While the titles may sound offensive - they are excellent books - easy to read with excellent advice.

Boxers are very high energy! Lots of excercise is needed daily. Personally, I would make sure that the kids and the pup are not allowed to interact at all unless there is an adult present.

As for food - Boxers can be very gassy. Canidae is an excellent food as are a couple of the others mentioned earlier. I would avoid foods that contain corn, soy and any meat by products. Science Diet is pretty bad food for the price and not something that would make it in my front door. Neither is puppy chow.

My pom eats a cup of food a day and he weighs all of 8 pounds. Your pup most definately needs more then what she is getting. My suggestion would be a cup and a half in the morning, a cup and a half at lunch and a cup and a half for dinner. You will find that with better quality food, your dog is digesting and utilizing more of the food and pooping less.