1. Because Baby was what her husband called her and Suggs was her husband's name. She kept calling herself this name also because she wished her husband come to look for her. If she changed her name, he might not find her.
2. Sethe might thought that “Denver” was actually a pretty name for the newborn baby. She might want her baby to remember Amy Denver. And the name might be a wish for baby Denver to live a life like Amy Denver.
3. Because of him, Denver and her mother might live a better life than before.
4. From rejection to accptance to dislike.