Front ones are ok, drill or tigerseal its upto you
You'll still need to cut up the wing a little so that it doesnt stick out under the VT arch.
Also if drilling id suggest using small bolts instead of the clips on the front to hold it closer to the wing, bolt head slides in the clip slot, place bolt through the drilled hole and tighten up nut on inner side of arch until its fully flush
Theres also that bracket on the bottom of the front arch which bolts/attaches underneath the car- I cant remember exactly where it fitted, next time i jack my car up ill take a pic of it for you