1. An assigned admin cannot delete a page. The page can only be deleted by the admin who originally created it. Assigned admins also can't block/ban/forbid you from access to the page. I believe they may have changed the name of the page (which is only a possibility if you have less than 200 likes). Otherwise, Facebook won't allow a name-change. Go to the secondary account you used to create the page. It should still be there. Unless said 'idiot' abused it, and Facebook eventually banned it.
2. The payment information is not available to your scammer. Facebook only displays the last 4 digits of a credit card or the email address associated with a PayPal account. I would still constantly monitor my accounts to make sure no payment is being made without my consent. Better safe than sorry.
3. One doesn't simply turn new online BFFs into admins of their hard-earned virtual labor.
Best of luck, buddy!