Anonymity through paying by bitcoin
Anonymity:

Every transaction ever made in Bitcoin is public. You can see the most recent here:
https://blockexplorer.com/

What makes it anonymous, is that you may not know who owns which account number (Bitcoin address). If Privateinternetaccess picks a new receiving address for every transaction, it's very difficult for an outside person to see who is receiving your bitcoins.

Also, there are 'mixer' services which will send on the correct amount to an address, but maybe not use the same coins, so there's no visible link. blockchain.info has such a 'mixer' service.

Buying Bitcoin outside of US:

This question pops up a lot, so I'm making a site right now to show how to buy bitcoins from each country:
http://howtobuybitcoins.info/

Feel free to throw me any questions you have.