For mesh I use zipties or you can also use hotglue if you have it available and it will hold up.

Foglights it depends on where you are mounting them and on what bumper as well as the size of the light. I have a small set I installed on mine and I predrilled holes just big enough to put the screw through then used a backing plate to tap the screw through and it has held up fine for me.

Chips or holes in fiberglass? If its just little chips lie paint chips then sand it prime it and paint it.

If its holes, punctures, or tears then you would be best off getting some kitty hair and filling it from the backside then sand prep and paint.