Re: What spark plugs do you use???
Your best bet is to use the plugs that the motor was designed with, or the recommended (superseding) replacements.
You can find both at the the BRP store by looking up your motor, navigating to the cylinder and crankcase diagram, and clicking the number associated with your spark plug.
Once you have the original OEM spark plug up, click the magnifying glass for the superseding plugs.
http://shop.evinrude.com/
(click the picture of a parts diagram to get started.)