heavier beaters will take more force to move initially but will also hit the drum harder making for a louder sound. force equals mass times acceleration (f=ma) so a heavier beater moving with the same velocity will hit harder...pure physics. the length will have the same effect as having a heavier beater. when you move the beater higher above the cam you are increasing the arc length that the beater will travel, and if the pedal moves with the same velocity the head of the beater will cover more distance in the same amount of time, resulting in a harder hit. as for the way the pedal feels, the more force it takes to move the beater, the heavier the pedal will feel (law of inertia, an object will tend to keep doing what it is doing until acted upon by an outside force, in this case your foot). a light beater low in the cam will feel lighter but will hit with less force. a heavier beater high in the cam will feel heavier but will hit with more force.
for a nice muffled sound that isnt felt, the dw hardcore beater is all i can think of, but it only has that sound if you arent hitting hard enough to compact the foam past the point of the hard plastic center.