Adding avatar files to comments, detect username on comment form.

I use Dan’s Avatar Thingy Mod to show author avatars on each post.

Im opening subscriber level registration to my readers soon and I want their avatars to show along with their comments. I have no idea how to do this or if its possible at all. Is there even a way to add their user information to the comment form when they are logged in?

Any guidance at all is appreaciated!