Be sure to provide a den that is heated in the cold weather. This is strong material that will support itself and keep most small children's fingers out. Additionally, I strongly recommend raising the cage at least 2 feet above the ground to minimize parasites. Worming Standard worming for dogs or cats apply. Also, be sure you have a vet that knows about squirrel monkeys, an emergency is not the time to look for one.
Vaccines Go on the advice of a good vet who knows primates.
Vaccinations depend on what is endemic to your area. You may also want to consult with your nearest zoo. This paper is by far only an introduction to the care of squirrel monkeys.