> For example, make its value $1000.
The US used to have $1000 bills (and $10,000 bills, but those were only for internal gov't use). I'm pretty sure we're stuck with $100 as the top denomination to make organized crime more difficult.
Also, it's WAY easier to counterfeit a coin than a bill.
I think that depends. Some countries do integrate security features in coins.
The important question isn't whether it's easier, it's whether it's more cost effective. It's probably easier to counterfeit a USD penny than a USD $20 bill, but it would be less economical to do so.
(1) I don't know what the word is (linked?) but their currency is interchangeable. You can go to a Singapore bank with $100 BND and get $100 SGD (no fee) and vice versa.
I believe the term is "pegged"[1], although what you describe sounds like it is much more involved.
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