Do I Need To Show My Face to Panty Buyers or to Become Verified?

No, you don't need to.
Some panty sellers hide their face, some choose not to. This is your decision entirely and will not have any effect upon verification. However, if you aren't shy, including your face is always preferred to fetish buyers.
Please remember that anything you post on the internet is public, and you should not post anything you don't want people to see or read.