it depends on who is the person you’re observing (how old are they, what environment are they in, is it a group, etc.) and it depends on who is observing the person (how old is the observer? does the subject know they’re being observed? etc)

Recognizing behaviours can be as easy as observing people around you. I can’t help you at a deeper level because i haven’t studied it. But for personal observation, you can see that people who are violent are those you should stay away from…stuff like that.

Adapting to different behaviours is again a loaded subject. It’s such a broad question.

Ask it again in more specific terms and you’ll get more answers.