Wow, that was a pretty weird experience. I don't know about the fireball thing, I've heard of ball lightening(though I've never seen it), do you remember if there was a lot of static? I don't really know what the conditions would be like for that sort of thing. It sure does sound like an orb, given the fact that you felt somebody watching you and that your cat saw it too. Don't you wish that you had taken a picture.
I never have a camera around whenever something weird goes on.
I think the tail you saw may have been created by the brightness of the ball.