[_paralyzed_]

suicideneil says it's okay to run a single 4s with a bec, and he's like an encyclopedia of maxx knowledge. But yes, 2x2s is guaranteed to work.

Yes you can run the motor unsensored if the esc fails, but hobby king has some pretty inexpensive sensored esc's if you so desire.

Just google for values if you need to for the calculator, like diff ratio and what not.