All styling options can be found on your Theme Options page at Appearance > Theme Options > Styles. Anything outside of the scope of these options are CSS/style customization you’ll need to make to the theme to meet your specific needs. In terms of the design of the theme and the surrounding elements, there’s nothing different about pages built with the builder over pages that aren’t.
And if you’re dealing with specific elements in the Builder, you’ll see with use of an Inspector that there are tons of CSS class you can potentially use to style different kinds of elements.
For CSS changes, it’s a good idea to use a tool like firebug or Google Chrome’s built-in developer tools to locate them and then put the edits either in your child theme or in the “Custom CSS” option on your theme options page.
Also, here’s a helpful tutorial on how to use Firebug – http://vimeo.com/20917974. The only thing I’d suggest not doing is actually making edits to the theme’s CSS files, as it shows at the end of that video. However, the video serves as a good introduction to Firebug and how it can be used to find what CSS is effecting certain areas of your site without ever digging around in any files.