Questions on movie clip

1

There are some questions keep bothering me…

  1. I am now using empty movie clip and attached the movie clip to it.
    for example:

i name my empty movie clip as ball.
then my attach movie clip is ball1.
Is hitTest able to detect ball1?
Or how to make my movie clip to detect ball1 using hitTest?

I know about attach movie clip and remove movie clip.
I am using empty movie clip to attach and to remove.
However, is there anyway to completely remove this empty movie clip completely?

If I named an empty movie clip ball.
Am I able to >>

trace(ball._x);

I tried but my result is undefined.
Is there other ways of doing this?

>> I have to remove empty movie clip so that my hitTest is unable to detect it.

Thanks for helping me…>.<