There are hundreds of thousands of animals in animal testing. Many are primates like chimps, gorillas, and orangutans, but there are also mice, dogs, and horses going through this cruel process.
Loads of different mammals, fish, reptiles and birds can have creatures living off them (parasites). Most parasites don't actually kill the creature immediately, but to answer your question THOUSANDS.
It is unknown but millions of millions cells, at least, are in animals. The amounts also vary with the type and size of the animals. Humans have around 1014 cells (100,000,000,000,000).