Before replacing headlight bulbs, is it necessary to disconnect the battery (to avoid, for instance, generating fault codes)?
No need to disconnect the battery. As long as you get 9005 bulbs, it will be plug and play. Phillips diamond vision matches perfectly to the LED ring of the base. They don’t last very long ~150-200 hrs but they are worth it. It looks much better at night. If you want a more permanent solution, you might want to look into the Morimoto HID kit that K5 sells. It’s plug and play but you might need to remove the whole headlight assembly to install it.