You're young. The cardio will come with a couple of weeks of running. Google "fartleking" as that is probably the best form of activity for getting "rugby" fit You're reference to "football" and "contact" sports leads me to believe that you are based in the USA. The USA Rugby Website has a link on the main page called "Find a Club". That lets you search for the amateur rugby clubs based within a given area. Every major US community will have a club (many have several) and they are all happy to train new players.
Do you mean where as in 'what place' or as in 'what position'? The rugby USA website seems pretty good, you should be able to find a localish club I would think. As for position, well, who knows, it will depend on your abilities more than your size and weight, get to practice and see what happens.
On the wing
Well rugby is one of the best sports I've ever decided to play. It creates strong friendships and on top of it you get to relive alot of stress. Given what you have described, I think you would be in the scrum as either a flanker or a lock because of your height and powerlifting
