why you need to cut holes in it?the cable can be placed behind the area without trapping cables
well defo use the bonnet cable grommet,this can be found on the passenger side, right up under the foot well,and then the 12v you can either use the 12v from the head unit,or ive used the cigarette lighter cable for a source, just put a simple switch in if you dont want it on the all the time
im not to sure what matts on about though