At that stage of the game, it would be a decoration.
Fuel, machinery, ammo, clothing, etc. much more valuable.
You’d be better off buying boxes of toilet paper or tampons at wholesale.
Not really. Barter works, but the whole point of currency and coinage is to make transactions more liquid by not having to negotiate a wide array of divergent wants. Unless you believe that a post-collapse society is more or less stuck in a primitive late-nineteenth century lifestyle forever. If not, then you’ll have to have some sort of value holder for complex transactions but none of the other barter goods you mention have any serious monetary qualities.