I finally bit the bullet and created a new project to fool around with the farseer physics engine. After copying pieces of the simple game project that is provided at their site, I modified it to allow the addition of extra circles into the game. I think that this will help me get things moving in my shooter.
I believe I was neglecting to create new geoms for all the new items. Tomorrow, I'll take a look and see if I can get it working correctly.