I'd really appreciate your response. It's nice that I can ask questions on the internet when I need to because my vet. Make sure your kitten doesn't eat the string because that is dangerous. Kittens can vomit because of no reason or because of something like intestinal worms. I know its sounds gross but a local vet can easily treat it.
Puppies do seem to shiver more than adults.
Sometimes because they are cold or scared. But if your pup is playing so well with the kitten, you have one very well adjusted pup. It is not always normal for the 2 species to get along , but its the best entertainment when they play. In some ways I think with all pets it doesn't matter if you get htem when they are older because if you go to the shelter or to a breeder a lot of those animals have been handled a lot and are very well socialized. Occassionally you will get a pet that didn't get socialized and they don't know that your finger or hand or leg isn't something to nip or bite.