Not a fave of mine either, but most of the oozes have it. I don't 'think' it ignores hardness, but all I can find under the Subtype entry is: Some oozes have the ability to deal acid damage to objects. In such a case, the amount of damage is equal to 10 + ˝ ooze’s HD + ooze’s Con modifier per full round of contact. I adjusted the damage, and made edits that should address your other questions.