Cool, good you work well under pressure.
Uhm, as for the avitar, I don't think there is a limit. I put the original dragon picture on at 30 posts just because I couldn't figure it out before then. It is on the oatmeal colored bar here, when you click 'UserCP', and then you got down the list on the left hand side until you find the text 'Edit Avatar'. It is below 'Edit Profile Pic'.
As for the Avi, I just Googled 'Steampunk wallpaper', and took a desktop photo of what popped up. Lol. I did not know they were offering punk picks here. I am a doofus. oh well. But they had all kinds of stuff on the web, so that is how I got her.
You should be able to change yours. It's just the file size that matters. 64 mb or something, or 120x150 pixels, anyway it says when you try to change you pic, what size is allowed.