Yes you can still use it. It doesn't matter what you used to create your site (software or hard coding). All you're really doing is just uploading your files. If you follow the Transition Guidelines that SBI! provides you'll see that it's very straightforward. You don't have to know CSS, I just recommend it because it makes updating your site much easier.
http://help.sitesell.com/uploader/in...uidelines.html
Yes, you can still use the graphic library.