I'm not dave, but I've got some mileage down this road.
First - you don't need SketchUp Pro. There are plugins that you can get for free that will export to DXF or STL. They work just fine.
Second - you do need a CAM app - the PhlatScript thing (SketchUCAM, i think it's called now?) is there - it's available. It's pretty hinky, though. I don't like using it. I use vCarvePro. They recently put out an update that will let it import Sketchup files directly which saves a good deal of time and you no longer need the plugin (so there's two ways to avoid buying Pro!) :P
Lastly - There are things about the way SketchUp draws stuff that you will have to keep in mind. One big one, and this may be more the fault of he plugins I use, is that the exported vectors are made up of segments instead of arcs and curves. That can be a little troublesome like circles that aren't made up of enough segments get cut out with facets and aren't smooth curves.
The other thing is more about 3D abilities. Sketchup is NOT a 3D CAD program - it's handy for visualizing, and it produces very nice looking models but underneath, the number of polygons and segments it uses aren't necessarily visible in the Sketchup view as easily to see how they'll cut. Also, Sketchup simply can't handle millions of polygons as well as true 3D CAD apps like Rhino or the like. For really complex 3D shapes - super organic 3D curves and such - a true 3D CAD (or something like Aspire) would be better suited for the task.
It is helpful for a lot of things - It's a cheap way to get into it. And for 2D cutting, it's really a great way to go as long as you keep your segment counts up on your curves.