Those are extremely weak servos for a walker, only 1/3 the torque of "standard"
servos. Your bot will have trouble walking and even lifting its batteries. Frame
weight and carrying batteries are the primary obstacles with designing walkers.
http://www.instructables.com/id/Arduino-Based-Four-Legged-Robot/
My feelings is, the legs on that bot are much too long for the weak-kneed servos
cited above. OTOH, you learn by doing :-).