Dielectric grease actually will help with the electrical contact and will prevent corrosion, and will also prevent the boot from fusing to the plug like your current ones are.

I just use regular pliers to grip the boot of the plug, is it needed? No, but it's easier than squeezing as hard as you can and hoping your hand doesn't slip off and you bang up your knuckles. The pliers will give you more leverage as well and you will need it to get those plug boots off for the first time.