August was caught off guard, so he couldn't negate Gildarts magic in the beggining. When he realized what happened, then he was able to copy Gildart's magic. Also, I really can't recall the last time Gildarts use crush to attack someone by breaking them apart. When Gildarts used all crush or when he used attacks against Natsu, it just looks like magic blasts. Sometimes when he breaks stuff, you don't always see the square patterns either. To me the attack Gildarts used against August resembled disassembly.Able to negate being turned into mini August's but still cubed in the first place? Makes it sound like they're two different spells. Dunno man, seems a bit odd to me. From what i saw August was just cubed and slowly started falling apart, pretty different from what happened to Natsu who just instantly vanished. The only real similarity between the spells was the "square" shape of the blast that was fired at Natsu.
Not like Zeref's reformation had any gore either, half his torso was missing and there wasnt a drop of blood or any inked portions to speak of.
You said that Irene used the same amount of power that she uses to enchant the swords as she did the army. There's nothing to suggest that she did.Second origin doesn't give them MP, it gives ... origin for MP.
She use only one power - enchantment - put her (or another) magic into object.
Wall said that he can absorb lightning and metall is weak to it. But first, metall is not weak to lightning, not more than something else like meat, ice or tree.
He can absorb it, other can't. But it must still doesn't work on them.
Wall says that it's true that his species is weak to lightning. That alone proves his species would be weak to lightning. Wall simply modified himself to be able to store lightning. It is precisely because it's his weakness that he modified himself.