On Sunday I contacted Dan at Team Delta, who sold me the motor and controller. I described what was happening with the Sevcon Millipak controller and he was able to clarify things for me.
Issue 1: I could accelerate only very, very slowly, or else the system would shut down and the controller LED gave me a 9-flash error message, or "rotor position sensor fault". Turns out that I chose one of the initial controller setup parameters incorrectly. The controller uses current sensing and Hall effect feedback to servo the motor in either speed or torque mode, and I chose the speed mode when I should have picked torque. I don't have the equipment to change the setting, but Dan said he would put another controller in the mail to me on Monday with the correct setting.
Issue 2: I turn the keyswitch and I hear no "click" from the contactor engaging, and only get a 3-flash error message from the controller LED. This indicates a MOSFET short-circuit, which is internal to the controller. Dan indicated that the failure of the contactor to close confirms that this is the case. So, it's a good thing he's sending me a new controller anyway. He also mentioned that this is only the first out of about 58 of these controllers he's sold that has failed in the field.
So while I'm waiting for the new controller to arrive, I've been working on my front turn signals, using my usual medium of LEDs, acrylic plate, and 5-minute epoxy.