I was just in the YaBB site. WOW! Are we able to use all these different avatars and smilies that they show
As far as smileys go, I'm not quite sure what you're referring to because they only have the same smileys that we currently have installed. They do have totally different avatars, though - all either photos or drawings from movies or TV shows. If those are available for download, I'd certainly be willing to download and install them.
(But just as there are on our site, there are also plenty of avatars on the YaBB SE site that were created for personal use by the posters themselves...)
or is that up to you to decide what you want for the board?
Yes, we're free to install or remove whatever features, icons, avatars, etc. that we'd like.