I had company in town and took a day off from working on my game. I was also getting a little frustrated and felt I just needed some time away.
I found a much simpler example that I downloaded. After looking through the code, I tried to port some of the code over, but it didn't seem to do what I wanted. Instead, it now seems that the projectile and movement portion is flaky, since some is maintained by the physics engine and some is maintained by hand.
Not sure what I really want to do from here. I would like to try to get the physics working with my game, but I don't know that it would help make it any more fun, so I don't know that I want to spend a long time working on it.