Dog is "killing" her toys.. er help?

Your Grandma is right about a dog biting on a toy and shaking It. That is her instinct that she is killing a live prey. This does not mean that she will turn mean or start biting. It is Natural instinct for them. Your dog should have toys to play with. Try investing in more durable toys made for a larger breed of dog. As for your dog peeing on the carpet, you need to train her to calm down before you or anyone else pets your dog after entering. She is very excited to see you and doesn't mean to urinate on the floor. You Will both do fine. Try putting an entrance rug or runner by the door until you can train her not to urinate in the house.