A lot of work goes into engineering native code Excel add-ins that supply realtime market data in complex ways to spreadsheets. The Bloomberg Excel add-in is almost an entire application unto itself. On top of that, there is an entire team of people whose only job is to help customers develop custom spreadsheets using the data. On top of that, even more tight integration is available, allowing live charts and other components to be embedded into the spreadsheets. There are many who develop really complex "apps" in Excel and would not consider themselves programmers.
As far as the Bloomberg Excel plug-in goes, as long as you open the spreadsheet on a desktop with the Terminal installed, it will be displaying realtime data in the context of the logged in user (delayed/realtime, exchange permissions, etc.). If the spreadsheet is opened on a PC without the plug-in, it will just be missing any data that is supposed to be supplied from the plug-in. So users share spreadsheets as they would any other Excel spreadsheet.
As far as the origin of spreadsheets that Bloomberg helps create, they usually fall into one of two categories:
- There is a gallery of great complex examples that have already been created and designed (probably initially for one client / company) that are available to launch from within the Bloomberg Terminal w/ screenshots, descriptions, etc. They can be searched and when a user finds one they like, it is downloaded and opened in Excel, allowing them to further customize it.
- The user contacts the Analytics desk (chat/phone) and is either trying to integrate live market data into an existing spreadsheet or needs to build something complicated from scratch and does not know how to go about doing it. The team specializing in Excel spreadsheet builds takes over and works with the person to build what they need. In many ways, it's like a small consulting gig -- a service provided to Terminal subscribers.
Once the user has the spreadsheet via either method, they are free to share it internally like any other spreadsheet.