Definitely not. Manga skin is not edible. It's likely made of materials that are not suitable for human consumption and could be harmful to your health.
As of now, in the manga, the identity of Luffy's mom remains unknown. There have been many theories and speculations among fans, but no official confirmation.
As of the latest chapters, Big Mom did die. The circumstances surrounding her death were quite complex and tied to a series of intense battles and plot developments.