Added Italian tax schema

I've added Italian tax schema but I need help to understand some values:

type: should I use "iva" instead of "vat"?

we use different vat rate for different goods (foods, newspapers, etc), should I add:

<tax_rates>
    <tax_rate default="true">
       <rate>23</rate>
   </tax_rate>
   <tax_rate>
      <rate>10</rate>
   </tax_rate>
   <tax_rate>
      <rate>4</rate>
   </tax_rate>
</tax_rates>