On the front lip there are 4 flanges that hold the lip on underneath, which are supposed to mount with the stock plastic push grommets. These seem to be too short though sinve now it has to go through the lip as well. Is there anyway I can get longer ones about 1/4"?

i used the short ones but even though it didn't go through all the way up to the top into the car frame or whatever it is i just clipped it to the stock bumper flanges and its been holding on ever since. Since the stock bumper is connected to the car it wont go anywhere oh and also on the flanges i put a screw next to the push grommets for extra support. So i put 4 screws by the push grommets 1 or 2 in each wheel well and use the tape for the front part. make sure the surface is really clean or you'll find your tape unpealing like mine which i've fixed with more tape =] gl with your kit.

Its called take it to a body shop so you don't f-it up

no need to take it to a body shop its so simple they will basically do what you will do but your paying someone to do it put some elbow grease into your car and show your car you love it =].