Character sheet: you can google it, or use the veins of the earth one on the main LotFP page (see below).
I think there are a growing number of players in the US, but the best way to go about it is to find some gamers and get them into the game yourself.
New Referee book is in the works, and will hopefully be out soon, but not sure how soon.
Those free rpg day releases will not be found cheap in print, and are currently not available from the store. (You can get PDFs for free, see below.)
You can’t change the currency, but google can help with this too. Just type in the euro amount and “U.S. conversion” to see what you’ll be paying. When you buy stuff, the conversion will be automatic.
I assume you’ve been here, but just in case, on the right side of the page are links to all the free stuff: http://www.lotfp.com/RPG/