On the Spolar unit and I suspect the P/W unit as well there is a hole in the base under the motor support and they fall through the bench top. In fact when I put mine on the Spolar the hole in the base fit over the hole I had already made in my bench top so I didn't have to change a thing just drill holes for the hold down screws.
You don't need to drill a hole in your bench, although it sure makes it handle.
The motor is mounted on a 4" square channel (I think that's the size). The loaded shell drops out of the press, down its chute, and back through the square channel to the rear. At that point you could drill a hole in the bench, and just let the shells accumulated on the bench top behind the electric drive.
By all means go for the auto drive, it's a great accessory.
I mounted my PW on 3X3 pieces of wood which raised the base plate above the table surface, allowing clearance for a baking tray to slide behind the machine to catch the loaded shells. It holds 100 finished shells and is easily slid around the corner making it convenient to put the loads in the stacker thingey. Another advantage to doing this, is provision for routing the power cable for the controller box under the machine, and room to slide the control box underneath the loader, with just it's toggle switch sticking out.
Of course, it's not necessary to use a plained and finished piece of cherry for your project. (grin) ...mike