First, do not use any abrasives, whether pad or compound, to clean the knife. Your pattern will be damaged. The pattern itself will be fine but the etch that brought that pattern to light will be damaged. The etch does provide some protection from corrosion. When cutting tomatoes or other acidic things, rinse the blade and dry it, just as you would with a carbon steel blade.
Because of the different steels along the cutting edge, they abrade away at a different rate. That results in a "micro saw tooth" effect that makes it cut differently than a homogenous steel blade. That's about the most simple explanation. Both 52100 and 15N20 have more carbon than 5160. Properly heat treated, they should out cut 5160. As the 5160 is being abraded by use, it exposes more of the 52100 and 15N20. The 52100 is the highest carbon content in the blade, notwithstanding carbon migration. Other elements, like nickel, chrome and manganese, also have something to do with how the blade cuts and wears.
That's a really basic over view. There are much longer treatises that explain it.