Tax Identification Number & Users

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Hello I've been searching and I found the moduclo the NIF / CIF and the NIE, but my question is this.
This only works for Spain but if I put my tent in Italian, French and English and these users need to register with the Tax Identification Number "and only applies to Spain I can do?

Another question.

An example that is simpler:

User from Spain - Pepe http://www.latienda.com/ carried, 5 cm long screws -> the price to 1.00 €
User from Ireland - John will take http://www.latienda.com/ carried, 5 cm long screws -> the price to 1.10 €
Users from Italy - Maxi takes http://www.latienda.com/ carried,5 cm long screws -> the price to 2.10 €

pull everything through the same database but as the language will even out price or another.

In a country can have a user with different prices, and the supplier.

It can be done?