Ok I didn't read everything but I've just found the perfect and easiest way to get rid of the rivet.
From now on I'll do them all by this method (retina air etc).
Flat thin screwdriver and hammer:
Screwdriver was PARALLEL to the keyboard, as FLAT as possible, in order to make the rivet's head go up and leave its hole.
I killed many rivet before finding that, I was mostly cutting them..
Screwdriver as parallel as possible and gentle (almost) hit with the hammer and they just pop out in half a second.
Really easy cause the rivet isn't that much attached to the case..