Ashe is the best one to start out with learning AD carry I think. Graves/Cait are both good too because they are fairly simple. I'd stay away from Varus/Sivir/Draven since they take a little more skill (in my opinion). EDIT: to answer your edit, straight up damage ad carrys are Graves, Cait, and Trist. (you can get Trist for free if you don't already know. Just like the Riot facebook page) [Edited on 06.15.2012 9:24 AM PDT]