The CTL-470 doesn't have touch input. If you intend to draw, invest on a medium sized model, such as the Bamboo Create / Bamboo Fun Pen & Touch CTH-670. It also has touch support.
As for substituting the trackpad, I don't think it has the same responsiveness, as mentioned in this Intuos5 touch review. I have this same model and it works great as a giant trackpad, but is definitely less responsive than a Magic Trackpad.