Sure, an adopted parent would get the vault key, but i doubt they would be allowed to use the money in the vault, especially from a family vault that doesn't in any way belong to them. Considering it's the magical world, one would expect that the goblins would be smart enough to stop even a guardian from entering someone's hereditary vault and mess around with it when they aren't a relative.

Come on, Xipho...holsters and armor? Please. There was nothing in the books that actually said that such things even exist. It never mentioned that dragon hide is used as armor...Fred and George buy it to look fashionable. Moody says don't put the wan in your pocket, but he never offers an alternative.

The whole point of a SECRET organization is to make sure that no one knows of it. And they are quite successful at that...Fudge thinks DD is using he students as an army, not knowing that Dumbledore already has the Order. If someone loses their job because of thier own indescretion, they would be booted from the order and obliviated, lest they reveal secrets again and jeopardize operations or whatever.

What do they need money to fund the war for? Bribery>Dumbeldore's too good in canon to do something like that. All they do is meet in a house that they don't have to rent, and eat food while discussing the war. They aren't buying guns or armor, cause it would be mentioned somewhere.

Agreed, they have invisibility cloaks, and since they are supposedly really rare, they that would have cost a lot. However, i don't see them using money for anything else.

Plot holes such as why the Weasleys continue to live in a hovel. One would think that they would use the money to improve their standard of living at least the tiniest bit.

Agreed, less paperwork, bot then one would think that books written by Merlin would be worth the paperwork required. If HP finds out, then tough shit...he's gonna find out about the money anyways, so just make a much larger effort o cover it up.