She inherited the sorceress' power twice; once when she was 5 years old or so, and the second time as an adult as can be seen in the ending.

As for Cid, he may be overweight now, but that doesn't mean he looked anything like that when Edea met him when they were younger. Believe it or not, people change as they age.

And that picture of Celine Dion and her husband scared me. *cries*