first of all, if you want advice, mine is to stop pining over girls all the time. second, you're going to a place in the country with two girls, both of whom are interested in you? how could you not appreciate what a great situation you're in?
You will probably go out with the new friend. The close friend wont care, but just be carefull... as you and the close friend will probably have a dirty wee afair at some point. Human nature!
yeah really, show another side of yourself occasionally... i would assume you'll go there and both girls will be there with their respective boyfriends...
Orgy then. I'd say, just start unzipping your pants in the middle of a neutral conversation. It works.
Dude, everything you're describing is IDEAL. You got a girl that doesn't want a relationship. A friend who's got a crush on you. Jesis. It's ridiculously easy.
Start massaging one. Then ask her friend to start massaging your shoulders. Then have them massage each other. Build from there.
Also do little things like kiss one on the neck while holding the other's legs sitting between them on the sofa. Or...compliment them both on something. I don't know the particulars, but you can't ask for a more perfect situation. Threesomes do happen.