I have been installing cable and satellite for 20 years and I avoid going thru any roof unless you install an emt pipe with a weatherhead and the proper flashing around it(similar to any vents you have). Sometimes you can get wires thru an existing vent's flashing on the downslope (depends on the roof material and flashing). Other than that just route the cables to an existing vent at the eave or side peak. Grounding should be the shortest possible interior or exterior. Primary target is the power mast (out a ground block near the dish), secondary a water pipe or ground rod. I usually mount the dish near a ground if at all possible.