How to print from an iOS device to a remote office?
AirPrint isn't likely to help you here. It's a basically a local network only technology, because of how it functions, it's very unlikely that you could get it working over an iOS device's 3G connection. The only way I could see it working is with a VPN, but I'm not aware of any solutions that can pipe AirPrint over a VPN.

What I would suggest (in rough form) is using email or Dropbox to send documents to be printed remotely. Pretty much any document you can access on iOS can be sent via email or Dropbox.

The basic idea is a computer running in your office that monitors an email address and/or a Dropbox folder, and automatically prints email attachments or files in the Dropbox folder. How you go about this depends on what software you're running on that computer, but on a Mac, you could print email attachments using Mail.app's rules filtering and some AppleScript, or files in Dropbox using a Folder Action.