The maximum allowed picture attachments per post is 4. You may want to upload bigger pictures, that way people can click on the thumbnails to get a larger view of your baby. If you need to resize your picture, here is a link on that:
http://www.yorkietalk.com/forums/showthread.php?t=1994
Animated avatars are done by several YT members or you can make them (they are called animated GIFs) yourself with a graphics program.
Members can also have signatures, which is accessed under the User CP (
http://www.yorkietalk.com/forums/usercp.php?), where you can post a signature which shows up under each of your posts.