When I did mine the AmpedGarage brackets were specifically being made for a different driver, the Faital 4032 I believe. The inside circle of the bracket was just slightly too small for the Infinity driver, and I just made it big enough. As for the ears, I don't remember specifically which ears, but it was on the passenger side for one, and then the center driver. The problem with the center driver is that it meant I had to remove it after installing it and that was a lot of trouble because the screw closest to the windshield doesn't have much room for a tool to get in. I would recommend that you omit that screw and try putting the grill back on to see which part gets in the way and then remove the ear and fully put it back together. Cutting the ears off is easy, they are just plastic. I'm not sure if I really cut the driver's ear too, I just don't remember.
I am still very pleased with the sound. It is much more focused, the bass is deeper, and not shrill like the Tesla drivers were. I don't know who decided the Tesla speakers sounded good but to my ears they were terrible. It also helps to use a decent source. I don't know if Tidal is available to you in France but that is the best to use that is native to the car. I used Qobuz (from France) through a browser and that too sounded great, but only while parked.
Good luck doing the work. I managed to make it work and you can't see that I ever touched it. Take it slow and you'll be fine.