Any of the holes I don't need, I would weld to fill, grind smooth, and cover with primer filler, at the least, to limit corrosion. That's pro body work practice.
If you want them pretty, do body filler, primer, paint, after welding and grinding, on the pretty side; still prime the other side, or they'll rust from behind.
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OK, I see I'm about 4 months late. Someone dug up an old thread.
You do what you gotta do.
On the bumper repair. A dent that size in steel, the metal stretches some. As you are bumping it back into place (pointy hammer and dolly, bodywork tools) you can shrink the metal by heating slighty past a cherry red, then fast cooling with water. That's the old way. You can put 3-4 hours craftsman work into a dent that size.
Cheap way, more modern practice, just fill it with plastic body filler and file it smooth. Plastic is cheaper than labor.