If you want more info on the "brain", SEARCH for keyless entry, you won't get a answer from anyone here since this has been posted so many times. Some post somewhere will tell you not only how to determine if you have it, but what remotes you need and how to program them.
BTW, no Contour or Mystique ever came with the digital door keypad installed from the factory. Ford determined that the Contour wasn't worth offering the keypad on, probably because they knew they wouldn't sell many with it. Besides, where on the door would you put it and have it look tasteful? I've only seen two vehicles that pad looked decent on, the Continental and Mark VIII. Those are both 40k+ vehicles, and the pad is a membrane integrated into the door handle. On other Ford cars, the keypad is tacked on to the outside of the door, either above the handle, below it, or in the A pillar. Those locations make it look like an afterthought.