Are there restrictions on image file types that can be used as part of the new Offers schema? PNG, JPG, GIF, animated GIF?
Also, will these images be cached the same way images are now being cached inside email messages themselves?
The Offer schema doesn't introduce any additional restrictions on the image file types that are supported inside emails. Animated GIFs will be rendered as static.
The caching logic is the same that is used for images inside the email body.