1) Well, we know that CW did say this because the Omniscient Narrator, not just Mary or Anne, tells us that he did.

Frederick Wentworth had used such words, or something like them, but without an idea that they would be carried round to her. He had thought her wretchedly altered, and in the first moment of appeal, had spoken as he felt.

Yes, he has changed his tune, but since his new (and sincere)attitude is so much more flattering to Anne, she's not going to bring up the past.

2) I agree with Susan on this one. Anne believes that the revival of CW's love for her came first, and his changed opinion of her appearance was second, not the other way around. IMO, it's not that he previously disliked her looks because he was upset with her, but that now he sees her with the eyes of love, and before he didn't. (Apparently Anne is not vain about her own appearance - *she* doesn't think she's as pretty as she was 8 years ago, but she's happy that CW thinks so!)