Quick update on the quadrotor. I went through all of the motor wiring and found that the motors were hooked up to the wrong terminals! [This diagram][multiwii-diagram] plus watching the orientation of the machine on the configuration software helped me figure out where I had gone wrong. After that, I calibrated the throttle range on all of the speed controllers and then tried flying again.
Except, it still doesn't really work. I played around with it for quite awhile but one of the speed controllers is still basically either on or off. No proportional control at all. Also, I relocated the gyro and accelerometer board to dead center of the body, which helped a little.
And then, when I was holding it and playing with the throttle and trim on the transmitter, one of the motors stalled out somehow. I'm wondering if maybe the battery is low again. Going to throw it on the charger for awhile tomorrow and try again.