My LaserPoint has a ruler, but it's metric, not that it matters. The only useful purpose for that for me, is when I'm feeding a sheet into the cutter - I jog the vinyl back and forth and see how it tracks compared to the tick marks on the ruler. That tells me how crooked I am, and which way I need to make adjustments.
If there's a CleanCut Blade for the Prism, I'd look into getting a 60* and 45*, if they don't - I'd still get a 60* blade, because that will be helpful when you cut small stuff, intricate designs, or tiny text.