Try
This post from, like, yesterday regarding making scrollbars appear.
API Javadocs are our friends
Regarding the DND issues... well, I'm not really an expert on that. I don't know how much, if at all, you have already attacked this problem. It helps if you are familiar with the Java drag and drop API (which I am not, really).
What I do know is that
you should make the tab a drag source. That will let you pick it up. Then when you drag out of the window you can have your listener tell the tabbed pane to remove that tab. Since you don't really have a drop target other than thin air (i.e. the space on your screen not utilized by your Java program's windows), I'm not totally sure how to drop onto something, but I'm sure you can figure it out with some painstaking effort, sweat and significant profanity directed at Sun.
Sorry I can't give you much more than that.
Good luck!
Bill