I just went to the local computer shop, got a couple of old cards that were broken, and picked the one that I thought looked the best stuck behind the vents. No one will ever notice that it's not from a Casio.
As for cutting out the vents.......Dremel, Dremel, oh & Dremel.
It's never easy making that first step to cut something out of a helmet..(or anything for that matter)..Indecision and uncertainty are the bane of the Fett maker, but once you do it you'll wonder what all the worry was about.