ARCHITECTURAL MAILBOXES6200B-10 Oasis Jr. Locking Post Mount Mailbox, Black

Does this fit onto your in-ground post without an adapter plate?

I have lost one of my keys. the key maker said i need to get blanks from you. where can i order them?

What are the dimensions of the blank area under the lock? I'd like to order numbers too, but not sure how big.

Received mailbox today and only 2 of the 3 keys will open it. I know you can buy replacements or make copies but will the company provide one?