I don't think they change avatar limits since the whole point is that they can guarantee that no given page of posts will exceed a certain amount (and negatively affect someone with a bad connection). I could be mistaken though. I don't know about the rest either. Would be interesting to see if there is.
Avatar KB limit changes at ~10 posts or maybe depending on how long your account was active, but that's not the only thing I was focusing on. I was just curious if anything else was locked behind a post-count. I also just realized that the name change feature is available to me as well, so I goof'd there.