You really should try your cats out on a puppy. They will be totally intimidated by a large grown dog, and the dog might have an opinion about cats too. The cats will control the puppy and the younger cats will even end up playing with it.
I’m not home enough to train a puppy. I get tempted every time I see those adorable little faces, but I’ve seen too many untrained dogs. I had a senior collie for a few years pre-cats (only had one then, and he ignored her) and that worked out well for my lifestyle.