One zip tie through the loop at the top, hooks hook around the bottom of the radiator. No brainer, it will all make sense when you have the item in your hand. Its like the radiator was designed to have a cover mounted over it. Yamaha even sells an OEM radiator cover and i think the install also recommends using a zip tie.
No you don't need to plasti-dip it. Having more mass for heat to dissipate if anything should be better and keep the bike cooler. If It's aluminum anyway, then it'll get real hot when stopped, but also cool off really quick. If it's steel then it may get hot and stay hot, but should be relatively cool while moving.
I have one as well. It does what's intended to do and you can't really see it unless you go looking for it. Although it looks a bit much in the photos, it's actually pretty subtle once installed.
Easy to install without the need for removing anything and no tools needed. I also just used a ziptie. Hasn't budged.