You are quite right. I was about to reply to the grandparent that you have just described present day Zimbabwe. History repeats itself.

This is more economics than history. It’s a pretty simple set of reactions that can happen at any time. You could “repeat it” in parallel anywhere at the same time, if you wanted to.

Mostly, yes. Though whether people resort to commodity barter or an outside currency like the USD varies.

Sometimes both happen. Eg in Germany after the war cigarettes were a common currency, even among non-smokers.

But that's probably more a function of comparatively effective restrictions on using foreign currency directly, than anything else? Not sure.