Hey! It works!
I was just going to test out this restarting X thing that was suggested, so I casually edited xorg.conf (I commented out the mouse settings and made my tablet my "core pointer"). I just wanted to try editing the conf file so when I restarted X I could see if there was any difference. In fact, I was totally expecting X to crash, as I did something similar to what I did before and X wouldn't start. That way I'd know the edited xorg.conf file was being loaded when I restarted X.
But somehow I did it right this time. My tablet now works perfectly as my primary pointing device! The buttons are mapped, it's in the right mode, and the settings I give it take effect.
Huh. Got lucky on that one.
Thanks for the help!
Dave