What kind of dog is Pandy?

In your siggy, she looks like a Great Pyr to me or a mix of that breed. If that's so, this is perfectly normal behavior for the breed. Well, the cat part is. Cat aggression is extremely difficult to break. She needs to be restrained at all times if there is any chance she could to a cat or other small furred creature. The cats must always have an escape route--somewhere she can't follow them.

I have one dog that thinks cats are snacks. Kayleigh views anything smaller than her as prey and she weighs 120 pounds so lots of things are smaller than her! I tried for a long time to get her to co-exsist with the cats and had no success. She is now muzzled & leashed if she has to be near them. When Kayleigh gets her house time, the cats get locked up in different room.

The nipping people is a whole other issue. What were the circumstances when she did nip? Did she know the people? Where you there? How old were the victims? How did they interact with her? A good, reputable behaviorist in your area would be a good place to start with this behavior. Ask your vet for a referral.