Is there a place where all the multiplayer user and administrator commands are documented?

Of course! OFP's standalone dedicated server comes with both a user and an administrator command guide. The document files are normally named DS-User.rtf and DS-Admin.rtf respectively and they can be found in the SERVER subdirectory on your OFP: Resistance CD or within earlier dedicated standalone server download files, available from BIS' OFP downloads page, for example.