To 3: I think we shouldn't read too much into it. Central banks hold all kinds of assets for the illusion of giving their fiat real value. Of course gold and financial instruments like bonds. But also lots of stuff - rumors are even wine and iberico jamon and stuff.

I'll be impressed if central banks and banks exchange Bitcoin reserves with each other like they exchange gold or fiat nowadays. Then we will know that they see it as a currency and not as a security/asset.