Now when talkinng about about reserves, the first thing that should pop up in our minds is "stability." That’s why governments keep gold, and foreign currencies like dollars, and other assets that don’t easily swing in price. Now if a nation decides to bring Bitcoin as a national reserve it would immediately face some set of problems. One of which is "volatility," coz Bitcoin’s price tends to swing from time to time. Now Imagine government want to pay for foodstuff imports or maybe repay international loans, only to find that Bitcoin has dropped in price... That kind of shock could further bring about further crisis instead of solving one.
This one is correct, the government sometime use their reserves, it's not untouchable and they will hold for many years before use it. Although I don't know how much actually the government spent from their reserves. They can use Bitcoin, but not recommended if it's all Bitcoin.
I haven't see Bitcoin surge during crisis, but gold did few times.
We also have the issue of "Liquidity" Indeed Bitcoin is a liquid asset, but I don't think that it is deep enough to support a government moving billions in and out without shaking the market. This is because that kind of government sized transaction could shake the market.
I don't think this is correct, it's the same like the government sold gold, it would affect the supply/market too.