What question are you asking? Does the droid X need an Task Manager? If so, you'll need to ask someone who owns it already. But wait, nobody does. Guess you'll have to look in the future when you get one since your a "future Droid X owner". Good luck with your quest for that answer my friend.
No, not at all.
Android can handle killing applications just fine on its own.
If its battery you might be worried about, it seems promising and Motorola added some nice battery managers to take more control of your battery life.
It has twice the amount of RAM that the original Droid has, so I seriously doubt it. The original Droid really doesn't require one either, although I do use an app that tweaks Android's native task manager settings.
My fiance has the htc Incredible, and he had to add the app kill. It was put on the phone for him at the Verizon store as a matter a fact. I appologize if my description of it is incorrect. But it has settings. You can set it to turn off all apps running in the background after a certain amount of time. My fiances is set for every 2 hrs. after he has been using it.