Hey Big Bubba, For cutting a bunch of patches without using a hammer, or raiding the junkyard, get a hole saw the right size, grind the teeth off, sharpen the edge by chucking it up in your drill motor, and running the outside cutting edge against a bench grinder. The inside can be sharpened with a stone, or ceramic rod. Then you just fold up the patch material, and cut five or six patches at a time.
As for your portable shooting bench, cruise the yard sales, and find an old metal adjustable height ironing board. You can usually get one of these for almost nothing.
Hungry Horse