Dang - you can explain social dynamics as much as you can explain technical data.IMHO charisma is like many other traits; some of it is innate and some of it is learned. How much of it you can learn depends on how much natural ability you have. I have seen people transition from being shy, stick in the mud types to the type of person who lights up the room.
Charisma can also be broken down into different mediums such as verbal and visual. Verbal charisma is knowing the right thing to say and is also impacted by delivery. Visual charisma relates to appearing friendly and likeable. IMHO visual charisma can be faked/mimed to some extent on the bandstand by simply smiling and acting as if your having good time (Assuming that is the fantasy your selling to your audience).
IMHO, probably a lot more charisma is faked than you are probably aware of. On occasion I have found myself at the home of some people that I considered extremely charismatic. In their home environment, they seemed every bit as dull an boring as I consider myself to be. Charisma is something they sort of turn on when they are in public. I am not necessarily certain they are completely aware of doing it. But IMHO charisma seems to be somewhat of a facade that they may wear or take off, depending on the situation.
IMHO image is about meeting the specific expectations of a certain scene; I.E. certain looks and behaviors. A look that is desirable in one seen may be inappropriate in another seen. Behavior that is seen as charismatic in one scene could be a turn off in another scene.
I am fairly introverted, but I can put on a costume and/or play a role on stage. AFAIK, a lot of performers are introverted.
This post pretty much explains it.