1) I do talk to myself a lot, but and tend to do a lot. So I guess I'm kinda active.
2) This really depends on my mood, if I'm in a good mood I'll probably be all polite but try to mind my own business. If I'm in a bad mood, you may not want to get in my way or look at me in a wrong way.
3) If I'm in a group I'm usually joking around, but still take things seriously if needed. I do tend avoid talking if I'm in a bad mood though.
4) Online can be combination of everything. Usually I'll try to get involved with whatever is happening, occasionally I'll just stick to lurking though. If I know the people though, I tend to revert back to my group persona.