A factory store is the best place to get hangtags! Just don't tell them you got the bags on ebay. If you carry your bag in, they can search for the best match, and they don't keep track of how many they've given you, so you can always get more. If you call
Coach, they'll likely just send you a metal one and it will take a long time to get it.
I truly doubt you will be able to get replacement hardware for a Legacy bag. They've recently changed their repair policy so bags older than a year aren't guaranteed. They have the hardware for classic bags available because they still make those bags, but they don't make anything with the same hardware as Legacy.
I don't think it is vachetta. At least mine aren't. They don't have the right texture, I don't think. Maybe the light color is? Anyway, I don't think the creed would read "burnished" if it was vachetta. Since it is burnished, the color isn't really supposed to be even.
I don't think vinegar would hurt any kind of leather.