I would say yes your sharpness is too high causing the noise/sparkles. I set mine about -8 to -5. My color is +3, brightness -1, DRC at 2. Since I have an Elite model I have some menu adjustment available to me that aren't available on the menu for a 5080. You will see people and calibrators enter the factory service menu on the standard KURO's to get to the additional settings available there. So you'll have to find what pleases you. Did you start off with 8th gen KURO recommended settings by D-Nice? I'm sure it's still available on AVS archived somewhere.
As far as a dead green pixel, try another input or another device to see if it's the device, input or screen. Try playing color break-in slides, you can download them elsewhere on this site onto a usb stick and play them back through the "Home Media Gallery" usb tv input. If it's the screen they say that playing a Pixar cartoon movie may help "unstick" a dead pixel, I don't know about that though(?). One dead pixel wouldn't even get a Pioneer response when the TV was new.
I can't speak to using gaming devices, I don't game.
Noise over HDMI wouldn't be normal except as to the sharpness or other menu settings. Again try swapping inputs, swapping cables, shorter cable, changing settings. Remember plasma does look different, some will say softer/film like, than other technologies.