RE: 1024 Resolution
It's like rack and pinion steering. The final output gear is in the middle of the servo rather than at one end. Instead of having a splined top sticking out of the case, a straight arm with gear teeth in it lies on either side of the gear so that when the output rotates one arm gets pushed one way and the other is pushed the opposite way. The linear servo has force and speed rather than torque and speed, its a simple matter of varying the gearing to get a range of forces and speeds just as with rotary servos.
In this photo you can just see the teeth of the output rack. The tiny hole conatins a screw connected to the feedback pot, so with a jewellers screwdriver you can adjust the centering of the arms.