Anything is possible my friend. To change the banner, look for banner.jpg in the zip of the theme. Its 480 by 270 I believe. You can create images using photoshop or PSP, or the image software of your choice. Remember to keep the dimensions the same!!!!! When you done with the changes, just upload the new image via FTP and be sure to name your new image banner.jpg also. It should show up on your site.
Rotating image script can be found at
This example is for Kubrick but works just as well for simple vanilla. A theme I used to use with rotating images.
you can see the rotation in action by visiting my site http://www.7milesdown.com hit the f5 button to hard refresh to see the rotations.