HI, i beleive that spirits are all aorund us all the time too. I have experienced much of what you describe soul- and i have a similar dog story!!
Back when my Dh was DBF - he had a dog who got hit by a car in front of his new house the day after he moved there- i had one of her puppies and when i moved in to the house- my puppy would run aorund the house "chasing" something at night. We would sneak out and spy and he was running up and down the hall way like he was playing with another dog!! We think he was playing with his mum!!