The Siberian Husky is not a one-person dog. Nor is he a guard dog. He might let you know someone is around, but he has no concept of protecting you. The Siberian is a friendly and gentle dog who is not overly suspicious of strangers or aggressive toward other dogs.
The short answer is yes, it's entirely possible to have RA in your jaw-RA affects joints and your jaw is a joint. In my personal experience, I find jaw pain one of the most difficult to cope with, it's as if it permeates everything, making it impossible to ignore.
The degeneration caused by RA tends to affect the smaller joints in the body first, namely the joints in the fingers, hands, and feet. The damage then spreads to other major joints in the body. RA usually affects the body symmetrically, which means the same joints on both sides of the body will show symptoms.