1. Deadly force, also known as lethal force, is use of force that is likely to cause serious bodily injury or death to another person. In most jurisdictions, the use of deadly force is justified only under conditions of extreme necessity as a last resort, when all lesser means have failed or cannot reasonably be employed.
2. Using the back of your elbow or open hand to smack someone is commonly used when they're consistently resisting arrest as well as using your asp in certain situations, that's what it's for.
3. I don't know where you got that from but watch this https://www.youtube.com/watch?v=49b8EJFqqPQ
4. Not to sound rude but no shit sherlock. Depending on the offence being committed of course you want backup if you can get it.
5. They do indeed have many police powers.
In addition, why do you think police officers are so tense and always on the lookout. Last night an NYPD Officer got stabbed in the neck, the suspect grabbed his gun and shot two other officers.