You can speed up your drupal load times a bit if you compress or aggregate your css files. Drupal can do this for you!

Simply visit Admin > Site Configuration > Performance and enable Aggregate and Compress CSS files. Submit the page and check out the results. All of those @import() calls will be condensed and you'll notice just one css is loaded.

There's a line between embedding images in HTML and applying the image as a background image via CSS. I often see them used incorrectly.

It all comes back to semantic markup. Semantic refers to meaningful, logically arranged (X)HTML markup. The content on a webpage should be in semantic markup. It should be readable with or without stylesheets, or in a plain text browser.