Answering the last part first, Connie is definitely in conflict with herself-as are most 15 year olds. She doesn't know exactly what she wants and is torn between what she feels she should be and what she really wants. Neither she nor the reader know exactly what this is.
Connie, the protagonist, is in conflict with Arnold because he represents the ultimate wild side- some argue that he even represents the devil. He plays mind games with her and manipulates her into doing exactly what he wants. She tells him he is crazy, but she ultimately succumbs to his persuasion as he tells her that the place where she was doesn't exist anymore.