Body language during communication can mean many things, the person might want to see if the person is following along to what they are saying or they just feel as if they are not communicating properly if its not used. With that said not a lot of people use body language, most people who seems to use it are speech givers, or public talkers. Maybe its a nervous habit for some, but its not a reliance so no I don't believe they do.
Either or, depending on the person. Shy people don't use much hand movements and seem to fidget whilst outgoing people use lots of hand movement and body language defines them as a person.
