Feliway is ment to help calm a cat down and to lessen stress. So if the cat is biting because it's upset or stressed, then yes.
If, however, the behavior is something it's Always done, then the problem is Training- so Feliway wont help much. You would need to Train the cat that this behavior is a problem.
When cats play together (or fight) they bite, a cat has to be trained that they have to be more gentle with people.
It depends why your cat is excessively licking himself. If stress is the trigger, then a Feliway Diffuser may help.
separate them
Feliway is a synthetic version of of feline facial pheromones which can be used to stop or prevent a cat from spraying. Additionally the pheromones can be used to calm cats during stressful situations like new places, traveling or even visits to the vet. See more about the product here: http://www.vetdepot.com/feliway.html
knock her teeth out
You will have to train them to stop biting because changing their teeth is cruel to the cat or kitten.
rip out his teeth
yes
People might bite their nails because they are nervous or bored. To stop biting your nails here are a few easy steps: 1 thing to do is to occupy your hands by knitting coloring or anything else that occupies your hands. If that doesn't help try to occupy your chewing. To do this chew gum or a toothpick. And finally you need the WILLPOWER to stop biting your nails. By doing this you can stop. Glad to help!
hit them
shave it off
How to stop biting my nails
It means to stop biting your fingernails. "Monkey on your back" is a slang term for any addiction or very bad habit. They are telling you you must get over your bad habit and stop biting your fingernails.