Help on WIX website (check out & VAT problems)

I have a website where i sell software licenses. I have a problem that on the checkout page and product page as my VAT for Spain 21% isn't showing up I need this fixed. As well I want customers who buy 1 product to pay full price but the second product they buy should be on a reduced rate. And last problem if a customer buys 10 products they get a 10% discount this needs to be added too.