we can't get a euro plus account without a european CC iirc
You can buy membership vouchers. http://www.game.co.uk/en/playstation-plus-subscription-1-year-142948?pageSize=20&categoryIdentifier=203135&attributeName1=Catalog_GameSalesCatalog_EN_GB&attributeValue1=4294965602
I think you can buy direct from the store as well, just use network cards to fund it.
Correct, however I'm not sure if US residents can buy from GAME in the UK. I would personally recommend PCGameSupply instead : http://www.pcgamesupply.com/buygames/sony-playstation-network-cards/
About the same price according to converters, Paypal available, and automated delivery (takes 30 mins at most).