It is the best way to conrol inflation. Inflation harms everyone.
Depends on how much the Europeans want our stuff, and how much they want to spend on American goods.
It's more reliable than nothing...
If only one country did, it would be bad. If every country did, it would be bad.
Abolishing the gold standard was vital to the U.S. making it out of the depression.
I don't know enough about the US but China certainly shouldn't adopt the gold standard. 1) There isn't enough gold to go round. 2) Mining gold disposes a lot of slag and is highly polluting. 3) It just makes things less flexible. 4) Inflation can be controlled without the gold standard, e.g. increase direct taxes, decrease government spending, increase required reserve ratio, increase discount rate, OMO selling of bonds...