Go to the TubeBuddy website and click on the "Promo Materials" section. Copy the URL for "Most Recent Upload" and add it to your signature. As for your banner, you add the banner graphic to the signature and place it as an image versus as an attachment. Signatures use BBCode, so you can find a lot of tutorials on how to do advanced formatting in BBCode all over the Internet.
I think that should answer, so I am marking this question answered and closing to further replies. You know how to reach me if you feel this didn't fully answer your question.