To confirm, removing the Scale node does not appear to have much of an effect. The can object appears to drift slightly off to the left as the animation progresses.

Scale got added by Blender as part of when I setup the tracking scene (I believe). There was also a distort node that was blurring the edges of my scene that got deleted. Second question: I'm actually not sure which I did or that I even know that there's a difference. I just checked tripod, selecting a 15-frame range, selected the whole kit under refine and hit solve camera motion.