Will ThemeFrame allow integration of scalable background images? I've perused the instructions at http://forum.bytesforall.com/showthread.php?t=11763, but I assume this relates to any wordpress theme, but my question is whether or not the ThemeFrame app will do this for me when I am constructing a theme. Thanks!

You can apply all kinds of CSS to elements, including all properties that are used in that thread, so you should be able to do this ThemeFrame

Thank you very much for the reply. I'm new to WP and themes, but I have worked with HTML and CSS. Another couple of questions: Can ThemeFrame be used to easily apply changes to existing WP themes? That is, if I find a theme with a structure that I like, can I use ThemeFrame to customize the theme in a variety of ways?

No, you can not use ThemeFrame to modify other themes, you build themes from scratch.