I'll answer all the questions then.
1)
Always. I constantly change my avatar but I'm fairly sure it always remains pretty much the same. In general, the character, and even the avatar itself, tends to accurately represent my personality.
On this topic, I also feel some people have very distinctive personalities while others have more common place and less unique.
2)
Yeah, I think so. Then again, it's not like I haven't tried. Posting all over the place, PM'ing people all day long and this moderator ruckus has certainly helped.
3)
Honestly know people? Dunno.
But that I feel "that post is so like him" or "I expected him to post that", I certainly do.