I am replacing my picket fence and have already done about six 8-foot sections. I have several to go. I have used one screw on top and bottom of the 3-inch wide pickets and I really don't like the way the holes show. I tried painting them, but they're still noticeable. My questions are (1) should I be using nails instead of screws, (2) if I keep using the screws, do you think the pickets will eventually cup with only one nail on top and bottom (they're primed and painted white); (3) if I switch to nails and rent a nail gun, what type of nail should I use that won't rust or react to the cedar wood, and (4) should I use 4 nails total (two on top and bottom)? Thanks for any advice you can give me.