A plugin to make linking to Twitter users easier with shortcodes.
You may not. But it was a handy shortcut for me, and hopefully you'll find it handy as well.
No, in version 1.0.0 that was required, but with version 1.0.1 that's no longer necessary. A link should appear in your quicktag toolbar labled as "twitter" that will insert the shortcodes for you.