We Europeans have known for years what VAT is, Yes we pay it on just about everything when we buy something. IT is the equivalent of the Sales Tax in the US but is levied by central government not individual States, Counties, Departements or whatever else the country concerned calls its smaller administrative sections. Oh and by the way we also have a minimum value upon which VAT is claimed on an imported package.
Your last part does not make sense, If a bulk order goes to Europe it therefore has nothing to do with the US and no US Tarrif is therefore involved.
If it is then sent on to the US then it does come under US Tarrif rules and if there is a Diminimis then that would apply if the value of the package once it arrives in the US is under that.
Going through another Country and or being increased or decreased in size along the way is totally irrelevant as IT IS ONLY WHEN IT REACHES THE US THAT THE TARRIF APPLIES.