2.) The normal way to reduce costs is to invest more in better technology, not reduce salaries. If there is a lack of investment - as you indicate - the solution is there and not in the change of the UPU rules. The "easy answer" to blame foreign powers will not solve anything. More money has to be used for the infrastructure.
3.) It is normally cheaper to buy where something is produced - because otherwise, several additional companies have to make a profit from importing, distributing and selling. It is therefore normal that is cheaper to buy something in China than to buy the same, Chinese-produced article in a shop in the US. Again, to make Chinese shipping rates more expensive will not change that.
It is not surprising with such a focus on non-domestic causes the US trade imbalance gets worse.