- if so, what motors can i use?
For either method I would think standard R/C hobby servo(s) would be the simplest and least expensive form of motor control for opening and closing 'trap doors' or rotating a mechanical steering path. R/C servos are easy to use in arduino sketches and don't require any addition hardware like motor driver shields and such. Servos do however require a separate 5vdc power source to operate well as powering servos from a arduino's 5V shield pin is problematic from a current capacity point of view.
Lefty