That number is supposed to be how much of the tariff that the exporter passes through to the importer. Essentially this is a measure of how much the producers lower their profits to lower the price to compensate for the tariffs. In other words how much the producer “pays for” the tariffs.

This factor is “backwards”, in that it doesn’t represent how much the producer swallows, but how much they pass on to the importer. Trump’s calculations assume that the producer only passes on 25% of the tariff price increase, but the experts say the number should be much closer to 95%.

I have to idea what “4” means.

The US has been there before with the Nullification Crisis of 1832. https://en.wikipedia.org/wiki/Nullification_crisis?wprov=sfla1

Buy Canadian is best, but anything will do if it isn’t American.