not sure on question 1, my bike was jetted and rejetted by someone else...as for question 2, i have the same thing in the same spot, i think it is to run wires through so you wont have to drill a hole urself, if i ever have to wire something from the back to the front or to the battery that is the easiest spot, if u look in ur picture where the seat seals down they have a lil dip in the seal or ridge and i think if u were to run a wire through the hole then go through the little valley in the ridge then it can go to your battery or whatever.....question 3 i think means polaris