It is my understanding that the unbreakable potions does not mean that it is impossible for the items to get broken, Just makes it harder for them to get broken.
Damage will still happen.
No, the Description: +0.5% chance per point of equipment not taking durability loss during combat.
At level 200 Max. Modifier: 100% with 200 points
So it means at level 200 it could not be broken, othervise i don't see any point frome such kind of potion's