First of all, the "top sides" means the hull sides above the waterline and not the deck. Based on the photos, hardware removal comments, etc., I assume you mean the deck. Set the nonskid aside for now. You need to sand everything smooth so it is completely "frosty" in appearance (no shiny surface) and not just sand the "chips" on the smooth parts of your deck. You should clean the deck to make sure all waxes are off, so you are not sanding wax into your sanding grooves. The sanding of the deck not only smooths it out, but it gives the next coat of paint a "tooth" to attach itself. If there are shiny spots, then that is where the paint will chip off later on because of poor adhesion. Next you need to apply a primer for whatever paint you choose to finish with. The primer will more so help with the adhesion of the top coat paint you choose. Then you apply the color of the paint compatible with the primer. If you apply a really smooth coat of primer, there will most likely be a window when you can paint over the primer without sanding. But, if your primer surface is rough, then you need to let it cure and then sand it smooth (but not off) before applying the top coat color. When painting, two or more thin coats is better than one thick coat. Technique will vary upon whether you are rolling/brushing on the paint or spraying it on. Paint selection has to do with color choice (you said white, so most any paint will have white). There are one part paints that are cheaper (like Interlux Brightside) or two part paints (like Interlux Perfection or Awlgrip/Awlclear). The latter are linear polyurethane paints and the Awlgrip product is used by pros. Whatever you choose, read the instructions on the label carefully and stick with recommended products.