Or are these forms of address much older than I assume they are?
Was Abraham Lincoln calling his friends "dude" and "man"? Did he use other informal terms? Or was everyone just formally calling each other "sir" and "ma'am", even among their friends?
If informal personal address is a more recent phenomenon in English, when and how did it develop?
No authority, but i can offer perspective by noting that the informal "thou" form and the formal "you" form started to fade out about the time of the English Civil Wars. (Cromwell's era). They started to call each other by one form under the more egalitarian influence of Cromwell. They decided to address everyone with the formal "you" (originally reserved for royalty and one's betters). I sometimes wonder if we have so many chummy terms like "mate" "dude" "bro" so we can emphasize or informality when we are working with only one pronoun.