Is it possible to add funds to a US iTunes store account with Paypal?
Yes, you can only use PayPal with iTunes US, and in that PayPal, you'll need to have a US bank account or have your locations and any credit cards/debit's on there will have to be located in the US as iTunes checks for that as well. It all has to be in the US, and cannot have any other bank or CC company for any other country.