HI Bill that center of gravity means you measure "Back" on the wings, from the Leading edge, the stated measurement .Yours is 3 1/4 " THAT is the point ,where you want your plane ,to balance..

The high rate :is when you activate ,your high rate switch (dual rate),, on your radio transmiter. NOT all radios have this feature.does yours.?.. Normally giving a larger total movement, of the effected control surfaces on the air craft.......When switched to high rate, you`ll have a greater Total movement, of those surfaces,than if switched to LOW rate


High rate is: 3/8" up, and,1/4" down, from it`s "neutral position"

LOW RATE: also up, and down, from your "neutral position",. You need to check your manual closer for the measurements .Your post only has half the specs in it. But it`s the same sort of principal as the high rate. I hope that this is, begining to make a little more sense to you now DAVE B.

P.S If your TX doesn`t have the dual rate switch, you can split the differences between the, low and high. suggested rates to have a happy medium.You`ll need to make those adjustments, on your planes linkages. I`m thinking though if the plane came with a radio and reciever that it would be already set up for you...A , BIG , BUT here, it is wise to keep an eye on these sorts of things and to check to be sure things are correct..AN awful lot of wrecks over this type of stuff D.B.