re: second mouse,
Most modern gamepads have a couple of analog sticks on them. They wouldn't be nearly as nice as a mouse, but an analog stick would theoretically be closer to the smoothness of a mouse than key input.
I don't know if BAM can sample gamepad input, but if not, it's easy enough to use a 3rd party tool (discussed earlier).
So you could at least have one person on mouse and one on gamepad, and that could be interesting. A sort of built-in handicap, if you will. Players could also be encouraged to switch off every other game to balance it out. You could also just have both players on gamepads to keep it completely level.
Regardless, I think creating a decent AI opponent is going to be far more useful than worrying about accommodating a second human player. I recommend playing those "Shufflepuck Cafe" links that I provided earlier, so you can see what it's like to face different AI opponents. Those play right in browser.
Myself, I've had a couple of these Logitech gamepads (attached) for many years. They are cheap (only about US$15-20), very durable, nice quality, and widely available. They have both key-style (digital) and stick (analog) input, so you can switch around on the fly. Sometimes that's quite useful for certain games, when you want to slow down for a moment and use an input that's more precise.